[tsan] Fix aarch64-*-linux after D86377

All check-tsan tests fail on aarch64-*-linux because HeapMemEnd() > ShadowBeg()
for the following code path:
```
 #if defined(__aarch64__) && !HAS_48_BIT_ADDRESS_SPACE
   ProtectRange(HeapMemEnd(), ShadowBeg());
```

Restore the behavior before D86377 for aarch64-*-linux.