tsan: fix active mapping selection

[dvyukov]

Summary

Fix bug introduced by commit 5d106f16b972.
SANITIZER_IOSSIM is always defined,
it's the value 0/1 that's meaningful.

[DavidSpickett]

LGTM

I was looking at the # elif defined(__aarch64__) && !defined(__APPLE__) bit and wondering what went wrong there but this explains it.

(if it doesn't fix the issue I can get you the maps file for one of the failing tests)

[dvyukov]

In D107888#2939061, @DavidSpickett wrote:

(if it doesn't fix the issue I can get you the maps file for one of the failing tests)

Thanks for the offer.
However, the actual on the machine hasn't changed and the tsan mapping haven't changed, but the selection of the active mapping has changed. So what I did for another similar case is:

• a/compiler-rt/lib/tsan/rtl/tsan_platform.h

+++ b/compiler-rt/lib/tsan/rtl/tsan_platform.h
@@ -723,6 +723,7 @@ enum MappingType {
struct MappingField {

template <typename Mapping>
static uptr Apply(MappingType type) {

+ Printf("%s\n", PRETTY_FUNCTION);

switch (type) {
  case kLoAppMemBeg:
    return Mapping::kLoAppMemBeg;

This gave me name of the actual selected mapping and it was clear it's wrong.
So figuring out which mapping is selected now and which was selected before the change may be more useful.

compiler-rt/lib/tsan/rtl/tsan_platform.h

 #  elif defined(__aarch64__)
   return Func::template Apply<MappingGoAarch64>(arg);
 #  elif SANITIZER_WINDOWS
   return Func::template Apply<MappingGoWindows>(arg);
 #  else
   return Func::template Apply<MappingGo48>(arg);
 #  endif
 #else  // SANITIZER_GO
-#  if defined(__x86_64__) || defined(SANITIZER_IOSSIM) || \
-      SANITIZER_MAC && !SANITIZER_IOS
+#  if defined(__x86_64__) || SANITIZER_IOSSIM || SANITIZER_MAC && !SANITIZER_IOS
   return Func::template Apply<Mapping48AddressSpace>(arg);
 #  elif defined(__aarch64__) && defined(__APPLE__)
   return Func::template Apply<MappingAppleAarch64>(arg);
 #  elif defined(__aarch64__) && !defined(__APPLE__)
   switch (vmaSize) {
     case 39:
       return Func::template Apply<MappingAarch64_39>(arg);
     case 42: