Move signal_blocker to platform and use it by default in TEMP_FAILURE_RETRY.

runtime/bin/eventhandler_android.h

Index: runtime/bin/eventhandler_android.h
diff --git a/runtime/bin/eventhandler_android.h b/runtime/bin/eventhandler_android.h
index 2647164fbf31d90782a4cf978157dd85eb5548c4..6b1bec6cad6a9c2899892529343457370f3ac702 100644
--- a/runtime/bin/eventhandler_android.h
+++ b/runtime/bin/eventhandler_android.h
@@ -10,11 +10,13 @@
 #error use eventhandler.h instead.
 #endif
 
-#include <unistd.h>
+#include <errno.h>
 #include <sys/epoll.h>
 #include <sys/socket.h>
+#include <unistd.h>
 
 #include "platform/hashmap.h"
+#include "platform/signal_blocker.h"
 
 
 namespace dart {
@@ -40,7 +42,7 @@ class SocketData {
   void Close() {
     port_ = 0;
     mask_ = 0;
-    close(fd_);
+    VOID_TEMP_FAILURE_RETRY(close(fd_));
     fd_ = -1;
   }