[clock] Use the new _zx_clock_get_new version of the syscall

ZX-2187

Change-Id: I69559abd29133afa62256d4b5a9935f193f46c6f

[libc] Rename pthread_impl.h to threads_impl.h

Baby step towards separating pthreads out of libc

Change-Id: Ibb1ba6656c796218909f4a3451db9bb66b99fb80

[syscalls] Rename zx_time_get to zx_clock_get

This change frees up the get() method in for a zx_time_t accessor in the
zx::time class.

Change-Id: Ia4cdc7e3e558df5ba0cfeedb27a442abf4d6f305

[musl] Remove duplicate declaration of __clock_gettime

The other is in pthread_impl.h and already has the correct visibility.

Change-Id: Ieafb7dd9ef7667cdce1ab56aa9c76e74cde2a977

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[musl] Move __clock_gettime declaration into a header and dedup a macro

Change-Id: I9fd466b2b58c2bab7f528976373a7b1cd9d8e773

[musl][time] Support CLOCK_MONOTONIC_RAW

For now, Magenta doesn't distinguish between raw and adjusted
monotonic times. As we bring up time synchronization, we may need to
re-distinguish them. But there's no reason to punish callers of
clock_gettime in the meantime.

Change-Id: I8cb28e6fc545c79e263d4aea85118ec73a9cbad4

[magenta][syscalls] Add MX_CLOCK_THREAD to mx_get_time.

This provides a way to get the total runtime of a thread, which use is useful
for implementing CLOCK_THREAD_CPUTIME_ID, which can in turn be used for
benchmarks.

Change-Id: Ibdf40177c24bf0928bbcf2aa9dde4f15e8f9e8b0

[musl] Support CLOCK_REALTIME

This corresponds to MX_CLOCK_UTC. A little more work is needed to
actually ensure that the RTC is set appropriately, but that isn't this
function's concern.

Change-Id: I5584855ef0a00f70e68a248b9d3ae0d56b6ad067

[syscalls] stop calling deprecated mx_current_time()

Change-Id: Ie41017dacb4acbc0a03b62dde9252681607e0e1d

[ulib][magenta][runtime][musl] Give system calls _mx_* names, use them in musl

The mx_* name space is not kosher for the standard C library to use
for its own purpose. A conforming standard C program can define its
own functions called mx_* and this must not break the C library.

Give all the system call entry points in the vDSO names starting
with _mx_, with the old mx_ names as aliases. Use only the _mx_
names in runtime and musl.

Change-Id: Id01b57b87c0bb91733e9492159401ff019943822

[syscalls][api] rename _magenta_*() to mx_*()

The _magenta_ prefix is pretty unwieldy.
This change simplifies that a bit.

This was done mechanically, and boots, runs, and passes tests
on qemu arm64, amd64, and NUC.

Change-Id: I8eb07db6ed6f4b8cac96344cc4ad65ce3f85f917

[magenta] Initial commit