sanitizer_common: Introduce internal_madvise and start using it.

A recent change to sanitizer_common caused us to issue the syscall
madvise(MADV_HUGEPAGE) during HWASAN initialization. This may lead to a
problem if madvise is instrumented (e.g. because libc is instrumented
or the user intercepted it). For example, on Android the syscall may
fail if the kernel does not support transparent hugepages, which leads
to an attempt to set errno in a HWASAN instrumented function. Avoid
this problem by introducing a syscall wrapper and using it to issue
this syscall.

Tested only on Linux; includes untested updates for the other
platforms.

Differential Revision: https://reviews.llvm.org/D85870