Fix SamplingProfiler name tracking on thread change

Summary:
Record the name of the new thread when the sampling profiler is told
that the runtime has changed threads.

Reviewed By: lavenzg

Differential Revision: D69692667

fbshipit-source-id: ba972bab97a39a8489c24bb0d670438f763d81e9

Author: neildhar

lib/VM/Profiler/SamplingProfilerPosix.cpp

@@ -482,6 +482,7 @@ void SamplingProfiler::setRuntimeThread() {
   std::lock_guard<std::mutex> lock(profiler->runtimeDataLock_);
   profiler->currentThread_ = pthread_self();
   threadID_ = oscompat::global_thread_id();
+  threadNames_[threadID_] = oscompat::thread_name();
 }
 
 } // namespace vm

lib/VM/Profiler/SamplingProfilerWindows.cpp

@@ -223,6 +223,7 @@ void SamplingProfiler::setRuntimeThread() {
   CloseHandle(profiler->currentThread_);
   profiler->currentThread_ = openCurrentThread();
   threadID_ = oscompat::global_thread_id();
+  threadNames_[threadID_] = oscompat::thread_name();
 }
 
 } // namespace vm