tsan: better diagnostics for destroy of a locked mutex + a test

llvm-svn: 162022
diff --git a/compiler-rt/lib/tsan/rtl/tsan_sync.h b/compiler-rt/lib/tsan/rtl/tsan_sync.h
index c967130..89de81d 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_sync.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_sync.h
@@ -60,6 +60,7 @@
   SyncClock read_clock;  // Used for rw mutexes only.
   StackTrace creation_stack;
   int owner_tid;  // Set only by exclusive owners.
+  u64 last_lock;
   int recursion;
   bool is_rw;
   bool is_recursive;