ART: Add GetClassModifiers

Add support for GetClassModifiers. Add a test.

Bug: 31684578
Test: m test-art-host-run-test-912-classes
Change-Id: Ia14276d3139503ce35f7684bd846b371e9eafa25
diff --git a/runtime/openjdkjvmti/OpenjdkJvmTi.cc b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
index 5283919..75c314f 100644
--- a/runtime/openjdkjvmti/OpenjdkJvmTi.cc
+++ b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
@@ -546,7 +546,7 @@
   }
 
   static jvmtiError GetClassModifiers(jvmtiEnv* env, jclass klass, jint* modifiers_ptr) {
-    return ERR(NOT_IMPLEMENTED);
+    return ClassUtil::GetClassModifiers(env, klass, modifiers_ptr);
   }
 
   static jvmtiError GetClassMethods(jvmtiEnv* env,