[rtsan] Add syscall interceptor (#118250)

This is a complex one - `syscall` is used when people want to bypass
libc and make the call directly

However, this call:
* Has a variable amount of arg

[rtsan] Add syscall interceptor (#118250)

This is a complex one - `syscall` is used when people want to bypass
libc and make the call directly

However, this call:
* Has a variable amount of arguments (up to 6, typically)
* Has arguments that can be any type, (think of whatever arguments go in
to the libc call, or see more details here
https://syscalls.mebeim.net/?table=x86/64/x64/latest)


I've tried to put in a couple tests to ensure we aren't mucking with the
underlying functionality and they seem to be working.

show more ...