Amanieu d'Antras 636476bcc1 Remove obscure & rarely used ARM intrinsics
In almost all cases it is preferable to use the stable `asm!` instead of
calling these intrinsics.

This PR removes the following unstable intrinsics:
- `__breakpoint` Clang extension, not part of ACLE.
- `brk`: undocumented
- `_rev*`, `_clz*`, `_rbit*`: use methods on integer types instead
- `__ldrex`, `__strex`: deprecated in ACLE, hard to use correctly
- Register access API: API doesn't match ACLE, better to just use asm

Also considered for deletion, but not included in this PR:
- Barriers: `__isb`, `__dsb`, `__dmb`
- Hints: `__wfi`, `__wfe`, `__sev`, `__sevl`, `__yield`, `__nop`
2023-06-16 16:09:53 +02:00
..