Block other signals while handling a signal.

runtime/bin/process_android.cc

Index: runtime/bin/process_android.cc
diff --git a/runtime/bin/process_android.cc b/runtime/bin/process_android.cc
index 2567cbeaf2e123e8f4f7599bcb5dfca1f444e550..5d17d0426da2225fc3e8f5e7760998fd42a9f756 100644
--- a/runtime/bin/process_android.cc
+++ b/runtime/bin/process_android.cc
@@ -696,6 +696,10 @@ intptr_t Process::SetSignalHandler(intptr_t signal) {
     struct sigaction act;
     bzero(&act, sizeof(act));
     act.sa_handler = SignalHandler;
+    sigemptyset(&act.sa_mask);
+    for (int i = 0; i < kSignalsCount; i++) {
+      sigaddset(&act.sa_mask, kSignals[i]);
+    }
     int status = TEMP_FAILURE_RETRY_BLOCK_SIGNALS(
         sigaction(signal, &act, NULL));
     if (status < 0) {