[PATCH 0/3] MR4862: mach.c build warning fixes

[Marc-Aurel Zent (＠mzent)]

This replaces the deprecated `syscall()` to `__pthread_kill` with its wrapper version, which will continue working when the syscall numbers change (happens luckily very rarely on XNU compared to NT).

Also replaces the deprecated `bootstrap_register` with `bootstrap_register2` (which although being private is being used by `-[NSMachBootstrapServer registerPort:name:]`, and what `bootstrap_register` calls into as well).

Both of these are available on at least OSX 10.5+ as far as I can tell, so should be fine support wise.

I took the liberty to also slightly adjust the formatting of `void init_tracing_mechanism(void)` to better fit into the surrounding code.

For me this makes it so mach.c now builds with 0 warnings all in all.