Add missing PrintStopMessage runtime entry to arm64.

runtime/vm/stub_code_arm64.cc

Index: runtime/vm/stub_code_arm64.cc
diff --git a/runtime/vm/stub_code_arm64.cc b/runtime/vm/stub_code_arm64.cc
index e928011e953d6f99fc24269ae56e5d4085f5c5a0..4148925ece6ff501b25393e4ba0fb2c9cb793098 100644
--- a/runtime/vm/stub_code_arm64.cc
+++ b/runtime/vm/stub_code_arm64.cc
@@ -128,6 +128,13 @@ void StubCode::GenerateCallToRuntimeStub(Assembler* assembler) {
 }
 
 
+// Print the stop message.
+DEFINE_LEAF_RUNTIME_ENTRY(void, PrintStopMessage, 1, const char* message) {
+  OS::Print("Stop message: %s\n", message);
+}
+END_LEAF_RUNTIME_ENTRY
+
+
 void StubCode::GeneratePrintStopMessageStub(Assembler* assembler) {
   __ Stop("GeneratePrintStopMessageStub");
 }