[vm] Fix Android ARM32 build.

Change-Id: I9467bc4145f09ffbbf4a10ecde627dec59fc023c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/456140
Reviewed-by: Liam Appelbe <liama@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

runtime/platform/thread_sanitizer.h

@@ -54,6 +54,7 @@ extern "C" void __tsan_write8_pc(void* addr, void* pc);
 extern "C" void __tsan_write16_pc(void* addr, void* pc);
 extern "C" void __tsan_func_entry(void* pc);
 extern "C" void __tsan_func_exit();
+constexpr uintptr_t kExternalPCBit = 1ULL << 60;
 #else
 #define NO_SANITIZE_THREAD
 #define DISABLE_SANITIZER_INSTRUMENTATION
@@ -71,6 +72,4 @@ extern "C" void __tsan_func_exit();
 #define DO_IF_NOT_TSAN(CODE) CODE
 #endif
 
-constexpr uintptr_t kExternalPCBit = 1ULL << 60;
-
 #endif  // RUNTIME_PLATFORM_THREAD_SANITIZER_H_