[sanitizer] Implement GetRSS on Windows

[cryptoad]

Summary

Pretty straightforward, returning the WorkingSetSize of a
PROCESS_MEMORY_COUNTERS structure. AFAIU, GetProcessMemoryInfo is in
kernel32.lib for Windows 7 and above. Support for earlier Windows versions
would require psapi.lib, but I don't think those are supported by ASan?

[cryptoad]

@rnk, could you please take a look? Thanks!

[cryptoad]

Ping!

[vitalybuka]

They fail if I break GetRSS on Linux.
I didn't check if anything else is missing on windows to support soft_rss_limit_mb=

[cryptoad]

In D42822#1003689, @vitalybuka wrote:

They fail if I break GetRSS on Linux.
I didn't check if anything else is missing on windows to support soft_rss_limit_mb=

Currently Windows doesn't have a background thread that is needed for the RSS check (launched by MaybeStartBackgroundThread).
GetRSS here is implemented for Scudo support. The larger current WIP CL is at https://reviews.llvm.org/D42519, which includes the RSS test support (but it needs a lot of other stuff to land).
Scudo uses a per deallocation check as opposed to a background thread to not have to start a new thread.

lib/sanitizer_common/sanitizer_win.cc

void internal__exit(int exitcode) {
   BUILTIN_UNREACHABLE();
 }
 
 uptr internal_ftruncate(fd_t fd, uptr size) {
   UNIMPLEMENTED();
 }
 
 uptr GetRSS() {
+  PROCESS_MEMORY_COUNTERS counters;
+  if (!GetProcessMemoryInfo(GetCurrentProcess(), &counters, sizeof(counters)))
     return 0;
+  return counters.WorkingSetSize;
 }
 
 void *internal_start_thread(void (*func)(void *arg), void *arg) { return 0; }
 void internal_join_thread(void *th) { }
 
 // ---------------------- BlockingMutex ---------------- {{{1
 const uptr LOCK_UNINITIALIZED = 0;
 const uptr LOCK_READY = (uptr)-1;