Suppress data races under AtExitManager until its threading nature is underst...

tools/valgrind/tsan/suppressions.txt

 ############################
 # Chromium
 
 {
   bug_23433
   ThreadSanitizer:Race
   fun:*logging*SetMinLogLevel*
 }
 
 {
@@ skipping 138 matching lines @@
 {
   bug_61585
   ThreadSanitizer:UnlockForeign
   fun:pthread_mutex_destroy
   ...
   fun:NSS_Shutdown
   ...
   fun:*AtExitManager*
 }
 
+{
+  bug_61753
+  ThreadSanitizer:Race
+  ...
+  fun:*AtExitManager*
+}
+
 ############################
 # Data races in tests
 
 {
   bug_30582
   ThreadSanitizer:Race
   fun:*LongCallbackD*
   fun:*WorkerThreadTickerTest_LongCallback_Test*TestBody*
 }
 
@@ skipping 189 matching lines @@
   ThreadSanitizer:Race
   ...
   fun:gethostbyname2_r*
 }
 
 {
   Benign race in nss (PR_EnterMonitor)
   ThreadSanitizer:Race
   fun:PR_EnterMonitor
 }