refs #5874 fix a mutex init problem I caught while testing 5874

git-svn-id: file:///svn/toku/tokudb@51923 c7de825b-a66e-492c-adef-691d508d4ae1

ft/tests/cachetable-rwlock-test.cc

@@ -97,6 +97,7 @@ test_writer_priority_thread (void *arg) {
 static void
 test_writer_priority (void) {
     struct rw_event rw_event, *rwe = &rw_event;
+    ZERO_STRUCT(rw_event);
     int r;
 
     rw_event_init(rwe);
@@ -152,6 +153,7 @@ test_single_writer_thread (void *arg) {
 static void
 test_single_writer (void) {
     struct rw_event rw_event, *rwe = &rw_event;
+    ZERO_STRUCT(rw_event);
     int r;
 
     rw_event_init(rwe);