[musl] Rename zx_get_startup_handle to zx_take_startup_handle

The new name more clearly describes the ownership semantics.

ZX-2235 #comment

Change-Id: I887c1f2ad657e3aff9716b9f1865184cb8cf05f7

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n

This reverts commit d7c91f0a8a876bd4de8808595cafcd4f2c3fd7a1.

Change-Id: I5c61410f62850583a970d3ff2f44b6d58901509a

[revert] Revert "[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n"

This reverts commit 2d25909b7ab244d73172c9f5bc11d85b49ccefbb.

Change-Id: I09efe4e1d69d7aeadb051936d3ddc8237e7d39cf

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 4/n

Remove actual from zx_vmo_{read,write}
Mark zx_vmo_{read,write}_old as deprecated
Retarget most uses of zx_vmo_{read,write}_old to zx_vmo_{read,write}.

Still need to migrate a handful of uses of _old that had meaningful
usage of actual.
This is good enough to go ahead and migrate uses in Garnet and Topaz.

ZX-1802

Change-Id: If57329f9c5183a0dacd29083decbaf771925145f

[dash] Validate nodes length

Change-Id: I917998d77be2cd8a80970dd9838b7f6b32ddfed1

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 1/n

In preparation for changing the zx_vmo_read() and write() syscalls,
introduce aliases (zx_vmo_read_old() and write_old()) for the existing
behaviour, migrate zircon callers to the aliases, and mark the original
syscalls as deprecated.

Once the garnet and above layers have been migrated, the original
syscalls will be adjusted to remove the "actual" argument, and the
temporary _old() versions will be deprecated, and then removed.

ZX-1802

Change-Id: I2fab9a59caf4093fb585ada6015197017767aba2

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[dash] Migrate to the new MX_ error codes

Change-Id: I82e4ba00bc1cbe3609f74781b505d6476a7b2365

[processargs] tidy up naming and numbering

This cleans stuff up ahead of the addition of string tables for
the upcoming PA_NS_DIR and PA_NS_REQ types and the eventual
flattening of PA_MXIO_* to a single type, using subtypes for
protocol.

- Align names with current-day usage
- Organize numbering / ordering around subsystem usage
- Reduce "type" field to 8 bits
- Reserve space for "subtype" field
- Use PA_ namespace and shorter a lot of very long names

Change-Id: I5e59f412c3b9bd79d90f921a248a6d98d4b703bc

[dash] Pass command-line args to subshells.

Change-Id: I1db939d69bd71154e96cb533386f1380279daa09

[dash] Subshells inherit function definitions

Pass function definitions to subshells. To accomplish this,
instead of passing a single command to the subshell we pass a
list of commands, with the function definitions as the first
items in the list.

Change-Id: I0f9dd51e6aaa6bbcfac4acbb83003900fd6d8a72

[magenta] Migrate Magenta's uses of mxio_get_startup_handle

Leave the compatibility shim in place until Fuchsia-at-large migrates.

For MG-228: "get startup handles should not live in mxio"

Change-Id: I5bf53388585520bf7d4b5acc31902bfc7797489d

[dash] Add background execution support.

Change-Id: I735fa0dd2a0d3e38c887c039e42d604288d6b01d

[dash] Eval subshell commands after init.

Initialize variables from environment before attempting to
execute subshell commands.

Change-Id: I4916bbddf9893f7717dac080a20ac13cfbe6cd5a

Remove mx_size_t and mx_ssize_t types

mx_ssize_t is no longer used. mx_size_t is superfluous and
can be replaced by the standard C type size_t.

Change-Id: I2137af6f166099d2e8aaca4fab63ff101f2a43ac

[dash] Implement foreground subshells

Dash can now execute AST fragments in subprocesses, which means commands
like the following work:

$ (echo 42)
42

Change-Id: I66a994f9de9d3541d1c830c0db75ce09f3196e9f

[dash] Set the console title appropriately

Change-Id: Iba0e668c5fd945fe8a547d410151faaea7ec5502

[dash] Stop checking for new mail

There's no reason to check for new mail before every command.

Change-Id: I8ee01143feb39492136ddeb452184e0e03fc2b9b

[dash] Import dash 0.5.9.1

This is dash at revision afe0e0152e4dc12d84be3c02d6d62b0456d68580 from
http://git.kernel.org/cgit/utils/dash/dash.git/

Change-Id: I640f85e59520531ad7c65b7b35f00651e5cbc5d9