Enable Thread-Safety Analysis by Default

Summary:
With the new architecture of `AsyncDebuggerAPI`, we've limited the
multi-thread complexity to just that one class. Unlike the old
`CDPHandler`, we no longer have recursive mutex that can't be checked
with Thread-Safety Analysis (TSA), so all the new code can be validated
at compile time using TSA.

Reviewed By: fbmal7

Differential Revision: D53622570

fbshipit-source-id: 05d8cce28578dbf41233131b4db4b010017b7a7f

CMakeLists.txt

@@ -253,7 +253,7 @@ set(HERMES_USE_FLOWPARSER OFF CACHE BOOL
 set(HERMES_ENABLE_WERROR OFF CACHE BOOL
   "Whether the build should have -Werror enabled")
 
-set(HERMES_THREAD_SAFETY_ANALYSIS OFF CACHE BOOL
+set(HERMES_THREAD_SAFETY_ANALYSIS ON CACHE BOOL
   "Whether to compile with clang's -Wthread-safety")
 
 set(HERMES_ENABLE_WIN10_ICU_FALLBACK ON CACHE BOOL