Fix product and Mac build.

runtime/bin/platform_macos.cc

Index: runtime/bin/platform_macos.cc
diff --git a/runtime/bin/platform_macos.cc b/runtime/bin/platform_macos.cc
index 8e2fd187b911b5f03ddf882675e958544bd076bb..0c6de4ddac93d7de56b4f96e7baaa0822598e425 100644
--- a/runtime/bin/platform_macos.cc
+++ b/runtime/bin/platform_macos.cc
@@ -28,6 +28,12 @@ char* Platform::resolved_executable_name_ = NULL;
 int Platform::script_index_ = 1;
 char** Platform::argv_ = NULL;
 
+static void segv_handler(int signal, siginfo_t* siginfo, void* context) {
+  Dart_DumpNativeStackTrace(context);
+  abort();
+}
+
+
 bool Platform::Initialize() {
   // Turn off the signal handler for SIGPIPE as it causes the process
   // to terminate on writing to a closed pipe. Without the signal