[asan] On OS X, tag mapped regions with VM_MEMORY_ANALYSIS_TOOL tag

[zaks.anna]

Summary

This will tag all mmapped memory sanitizers use with "Performance tool data" when viewed in vmmap. (Even though sanitizers are not performance tools, it's the best available match and better than having the unidentified objects.)

[samsonov]

LGTM

[zaks.anna]

Committed in r251445.

lib/sanitizer_common/sanitizer_mac.cc

 extern char **environ;
 #endif
 
 #include <errno.h>
 #include <fcntl.h>
 #include <libkern/OSAtomic.h>
 #include <mach-o/dyld.h>
 #include <mach/mach.h>
+#include <mach/vm_statistics.h>
 #include <pthread.h>
 #include <sched.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/mman.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/sysctl.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 namespace __sanitizer {
 
 #include "sanitizer_syscall_generic.inc"
 
 // ---------------------- sanitizer_libc.h
 uptr internal_mmap(void *addr, size_t length, int prot, int flags,
                    int fd, u64 offset) {
+  if (fd == -1) fd = VM_MAKE_TAG(VM_MEMORY_ANALYSIS_TOOL);
   return (uptr)mmap(addr, length, prot, flags, fd, offset);
 }
 
 uptr internal_munmap(void *addr, uptr length) {
   return munmap(addr, length);
 }
 
 int internal_mprotect(void *addr, uptr length, int prot) {