Package Kit: Use an object_cache in kernel mode for decompression buffers.

The kernel heap only uses object caches for objects up to size 8192.
Larger allocations have to go through the raw allocator. That can
get pretty expensive.

Adding instrumentation around the malloc/free calls in this function
showed that on my machine, some 596ms during boot were spent on
*malloc/free alone*, all else aside. After this change, we are at
around 110ms, or a >5x improvement. Running an fgrep -R on /system/
after boot increased the cumulative time in memory functions to over
5 seconds, while after this change it is "only" 1170ms.

Honestly, it seems like the object depots should be able to be faster
than that, even if this function is called thousands of times. But that
is a problem for a different investigation.

It would be even faster for every consumer of this data in
packagefs just allocated one set of buffers up front, or at least
for a single "read session", but plumbing that all the way
through the myriad abstractions of the Package Kit will
not be easy, and is left for another time, as well.

package kit: Actually add support for B_HPKG_COMPRESSION_NONE

Until now we always declared in the HPKG header that the package file is
zlib compressed. For uncompressed files we would just store all
individual chunks uncompressed. Now we handle completely uncompressed
files slightly differently: We don't write the redundant chunk size
table anymore. The size savings are minor, but it makes the uncompressed
format read-streamable which may be handy.

Switch package file accessor classes to use BPositionIO

* PackageFileHeap{Reader,Writer} as well as Package{Reader,Writer} and
their implementation and super classes do now internally use a
BPositionIO instead of a FD to access the package file. This provides
more flexibility needed for features to come.
* BPackageReader has already grown a new Init() version with a
BPositionIO* parameter.

BPackageWriter: Add Recompress()

Allows rewriting an existing package file with a different compression.

Switch package kit to BZlibCompressionAlgorithm

... and remove the Zlib{Compressor,Decompressor} API.

Move package kit Zlib* classes to support kit

Also move to B* namespace and no longer expose the zlib dependency in
the headers.

Remove BPackageKit::BDataOutput

Use BDataIO instead.

Revert "Move ZlibDecompressor to libshared"

This reverts commit 9af2105d36856be60528c361edf14a263f242338.

Conflicts:
src/kits/package/Jamfile

Revert "Fix more issues detected by gcc4 compiler:"

This reverts commit 19f3bae0716c4eb7dd2a5716778560580be68071.

Fix more issues detected by gcc4 compiler:

More ssize_t/status_t mixup.

Move ZlibDecompressor to libshared

* This will be used to implement compressed http streams
* Remove the custom BDataOutput class, and use BDataIO instead, for
easier integration with existing code.

hpkg format: user big endian for chunk sizes

PackageFileHeapAccessorBase: Fix error output

PackageFileHeapAccessorBase: small refactoring

* Pull method DecompressChunkData() out of ReadAndDecompressChunkData()
for potential reuse.
* Also fix/improve some error output strings.

hpkg format: compress the whole heap

Instead of handling compression for individual file/attribute data we
do now compress the whole heap where they are stored. This
significantly improves compression ratios. We still divide the
uncompressed data into 64 KiB chunks and use a chunk offset array for
the compressed chunks to allow for quick random access without too much
overhead. The tradeoff is a limited possible compression ratio -- i.e.
we won't be as good as tar.gz (though surprisingly with my test
archives we did better than zip).

The other package file sections (package attributes and TOC) are no
longer compressed individually. Their uncompressed data are simply
pushed onto the heap where the usual compression strategy applies. To
simplify things the repository format has been changed in the same
manner although it doesn't otherwise use the heap, since it only stores
meta data.

Due to the data compression having been exposed in public and private
API, this change touches a lot of package kit using code, including
packagefs and the boot loader packagefs support. The latter two haven't
been tested yet. Moreover packagefs needs a new kind of cache so we
avoid re-reading the same heap chunk for two different data items it
contains.

package kit: Actually add support for B_HPKG_COMPRESSION_NONE

Until now we always declared in the HPKG header that the package file is
zlib compressed. For uncompressed files we would just store all
individual chunks uncompressed. Now we handle completely uncompressed
files slightly differently: We don't write the redundant chunk size
table anymore. The size savings are minor, but it makes the uncompressed
format read-streamable which may be handy.

Switch package file accessor classes to use BPositionIO

* PackageFileHeap{Reader,Writer} as well as Package{Reader,Writer} and
their implementation and super classes do now internally use a
BPositionIO instead of a FD to access the package file. This provides
more flexibility needed for features to come.
* BPackageReader has already grown a new Init() version with a
BPositionIO* parameter.

BPackageWriter: Add Recompress()

Allows rewriting an existing package file with a different compression.

Switch package kit to BZlibCompressionAlgorithm

... and remove the Zlib{Compressor,Decompressor} API.

Move package kit Zlib* classes to support kit

Also move to B* namespace and no longer expose the zlib dependency in
the headers.

Remove BPackageKit::BDataOutput

Use BDataIO instead.

Revert "Move ZlibDecompressor to libshared"

This reverts commit 9af2105d36856be60528c361edf14a263f242338.

Conflicts:
src/kits/package/Jamfile

Revert "Fix more issues detected by gcc4 compiler:"

This reverts commit 19f3bae0716c4eb7dd2a5716778560580be68071.

Fix more issues detected by gcc4 compiler:

More ssize_t/status_t mixup.

Move ZlibDecompressor to libshared

* This will be used to implement compressed http streams
* Remove the custom BDataOutput class, and use BDataIO instead, for
easier integration with existing code.

hpkg format: user big endian for chunk sizes

PackageFileHeapAccessorBase: Fix error output

PackageFileHeapAccessorBase: small refactoring

* Pull method DecompressChunkData() out of ReadAndDecompressChunkData()
for potential reuse.
* Also fix/improve some error output strings.

hpkg format: compress the whole heap

Instead of handling compression for individual file/attribute data we
do now compress the whole heap where they are stored. This
significantly improves compression ratios. We still divide the
uncompressed data into 64 KiB chunks and use a chunk offset array for
the compressed chunks to allow for quick random access without too much
overhead. The tradeoff is a limited possible compression ratio -- i.e.
we won't be as good as tar.gz (though surprisingly with my test
archives we did better than zip).

The other package file sections (package attributes and TOC) are no
longer compressed individually. Their uncompressed data are simply
pushed onto the heap where the usual compression strategy applies. To
simplify things the repository format has been changed in the same
manner although it doesn't otherwise use the heap, since it only stores
meta data.

Due to the data compression having been exposed in public and private
API, this change touches a lot of package kit using code, including
packagefs and the boot loader packagefs support. The latter two haven't
been tested yet. Moreover packagefs needs a new kind of cache so we
avoid re-reading the same heap chunk for two different data items it
contains.