Merge pull request #326 from ctiller/wakeup3

Initialize mutex

src/core/iomgr/pollset_kick.c

@@ -142,11 +142,13 @@ void grpc_pollset_kick_global_init_fallback_fd(void) {
 }
 
 void grpc_pollset_kick_global_init(void) {
+  gpr_mu_init(&fd_freelist_mu);
   grpc_wakeup_fd_global_init();
 }
 
 void grpc_pollset_kick_global_destroy(void) {
   grpc_wakeup_fd_global_destroy();
+  gpr_mu_destroy(&fd_freelist_mu);
 }