[fdio] Move headers into lib/fdio/...

Change-Id: Ie8d74e716da913bf6e2672c4acf8cd67b4962b7f

[fs] Execute fs integration tests on mount point in local namespace

This patch reduces the dependency on global "/tmp".

ZX-1722 #comment Done
ZX-1939 #comment In Progress

Change-Id: Ic0ec2e1fe52fafc0e0edb65fa2884af970d9571f

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[fs] Add test for remove

Not checking for a distinction between 'rmdir' and
'unlink', since they currently send the same request to the
filesystem server.

Change-Id: If57cbbb8b92d4cdc9667d15bd9fb774d23a4a4a2

[utest][status] Use the MX_OK and MX_ERR_* mx_status_t names

Change-Id: Ia395c985d6d13cdad97e66d92933d13ddb75c8b8

[mxio][fs][musl] Add support for realpath

Non-traditional POSIX gotchas:
- Magenta cannot rely on proc
- Magenta does not support symlinks

Magenta-specific implementation:
- For absolute paths, open / canonicalize / verify
- For relative paths, copy cwd, append relative path,
and canonicalize.

MG-839 #done

Change-Id: I66949074ee76eea79d54bc3e11f3ebec02d167d9

[build] Support for LTO and ThinLTO in userland

This adds support for LTO and ThinLTO; currently it's only supported
by userland applications and libraries, the kernel still has some
issues which should be ironed out in the future.

Change-Id: I097f0e7f1ea1a35044077e0a1bd90e88d94faefd

[fs] Fix an out-of-bound arrary access issue

- 'PATH_MAX' is declared as 4096
- 'WPATH_MAX' is declared as 4096*2
- In wrap_path fuction, data from an array with 'WPATH_MAX' will be copied
to an array with 'PATH_MAX', causing buffer overflow.

Change-Id: I64845d84c07aa8116671e9e9cd8c1702ece83232

[mxio] Implement renameat, test it.

- Refactor "two_path_op" into "two_path_op_at", similar
to the unistd implementation of unlinkat.
- Remove an error case for "two_path_op", where a stack-based
buffer isn't large enough to hold two names, since we can
statically assert that the name will fit.

Change-Id: Ib47e2bf3bc433fb3b1d9f7e80b42929d07d5df4c

[fs] Add rename test for mixed absolute / relative paths

Change-Id: I1d0e0a2e7286330ac83cd0fcd9f4970678108f3c

[fs][utest] Fix path wrapping bug for opendir

By wrapping opendir in "wrap.c", the DIR* return argument
was smashed into an int, when it really should be kept
as a pointer.

Change-Id: Ieee5b9830d8c01c1a1f413ded5a1ba803a139e4c

[fs][minfs][memfs] Add support for unlinking open directories

- Update tests to allow these "empty, unlinked" directories.
- Update test suite to use "rmdir" instead of "unlink".
Exclusively for clarity; they functionally identical at the
moment.

MG-629 #done

Change-Id: I37024b873471639a83562fe9dfb68e18e4e1d3ee

[fs] Converted filesystem test suite from uapp --> utest

- This is possible now that we can identify "large" tests,
and prevent them from executing by default.

While I was there...
- I also fixed up the "test random op" condvar race contition
that previously plagued the concurrent "rw workers" test.
- Stdout spam reduced for the maxfile test.

Change-Id: I87fd25b6312d3490fa7842b9de22826646743d2a