[build] Make a number of static libraries build with -fvisibility=hidden

ZX-1895 #comment
Test: CQ

Change-Id: Id3252fcb1de5a6f6e1897da86fba92e2be9d0319

[compiler.h][fs] Remove DISABLE_THREAD_ANNOTATIONS from compiler.h

This mechanism is used by some filesystem code to conditionally
disable thread annotations. This is done for the sake of also building
code on the host.

This logic is specific to the filesystem code, and should not be part
of the public Zircon ABI. As such, this CL moves the conditionals into
the filesystem code itself.

Test: built with all compilers; CQ for mac; manually broke threading
analysis to verify that clang is still running the instrumentation.

Change-Id: I9c6453198c637fd03c1238d1c9790cb69ba11b6a

[fvm][zxcrypt] Refactor libraries to avoid fdio dependency

ZX-2266 #done

Test: Refactor; relying on exitant library/driver tests.

Change-Id: Ia54acac0fb8056c91b26c097a8efae22dd0c5b3a

[fvm] Add host & target side support for compressed sparse file

Change-Id: I2ba9350cfbc98e96de7fc0a7a253e9c560ba208b

[digest] Switch from cryptolib to uboringssl

This CL switches the SHA-256 implementation for ulib/digest to use
uboringssl, which includes optimized assembly and hardware acceleration
to provide better message digest performance.

Change-Id: Id3dedbc8232b4f4491b19fe46ef9e1415eea7358

[fvm] Add host-side tool

Example usage:
truncate --size=1g blobfs.bin;
./build-zircon-pc-x86-64/tools/blobstore blobfs.bin create
./build-zircon-pc-x86-64/tools/fvm sparse.bin sparse --blobstore blobfs.bin

Change-Id: Ifc44ea30d0cf68e3914d4e8591fa8c65998ba9ce

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[zircon][mxtl->fbl] Rename mxtl to fbl

Change-Id: Ie21b6498e1bfb0a7fa0315e40b9e5c3ee78646be

[fvm] Initial commit of Fuchsia VPartition Manager

Change-Id: I1dd488889dd440814277629ffbcfd6d57cf30f47