MIPS64: Enable StringCompareTo and StringIndexOf stub tests

art_quick_string_compareto and art_quick_indexof have been implemented in
    https://android-review.googlesource.com/#/c/172321/ .

Change-Id: Ic75d3a614e1a01a4a378db597021b952f9422d50
diff --git a/runtime/arch/stub_test.cc b/runtime/arch/stub_test.cc
index 8746bad..2cb2212 100644
--- a/runtime/arch/stub_test.cc
+++ b/runtime/arch/stub_test.cc
@@ -1193,7 +1193,8 @@
 
 
 TEST_F(StubTest, StringCompareTo) {
-#if defined(__i386__) || defined(__arm__) || defined(__aarch64__) || (defined(__x86_64__) && !defined(__APPLE__))
+#if defined(__i386__) || defined(__arm__) || defined(__aarch64__) || \
+    (defined(__mips__) && defined(__LP64__)) || (defined(__x86_64__) && !defined(__APPLE__))
   // TODO: Check the "Unresolved" allocation stubs
 
   Thread* self = Thread::Current();
@@ -2042,7 +2043,7 @@
 }
 
 TEST_F(StubTest, StringIndexOf) {
-#if defined(__arm__) || defined(__aarch64__)
+#if defined(__arm__) || defined(__aarch64__) || (defined(__mips__) && defined(__LP64__))
   Thread* self = Thread::Current();
   ScopedObjectAccess soa(self);
   // garbage is created during ClassLinker::Init