Remove failing check from platform specific darwin lsan initializer

[fjricci]

Summary

We currently don't have any platform specific darwin
lsan modules, don't force failure if they don't exist.

compiler-rt/trunk/lib/lsan/lsan_common_mac.cc

 }
 
 u32 GetCurrentThread() { return get_tls_val(true)->current_thread_id; }
 
 void SetCurrentThread(u32 tid) { get_tls_val(true)->current_thread_id = tid; }
 
 AllocatorCache *GetAllocatorCache() { return &get_tls_val(true)->cache; }
 
-void InitializePlatformSpecificModules() {
-  CHECK(0 && "unimplemented");
-}
+// Required on Linux for initialization of TLS behavior, but should not be
+// required on Darwin.
+void InitializePlatformSpecificModules() {}
 
 // Scans global variables for heap pointers.
 void ProcessGlobalRegions(Frontier *frontier) {
   CHECK(0 && "unimplemented");
 }
 
 void ProcessPlatformSpecificAllocations(Frontier *frontier) {
   CHECK(0 && "unimplemented");