Show ArtMethods in imgdiag

Since ArtMethods were moved out of mirror:: classes imgdiag does not
show information about them.  Diff ArtMethods to facilitate finding
dirty memory there.

Bug: 38173645
Test: imgdiag --boot-image=/system/framework/boot.art --image-diff-pid=`pid system_server`
Change-Id: Icd86a9ef14d5177a297026c22c81c080f5c85fc1
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 4161754..835d940 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -8368,6 +8368,10 @@
       (quick_generic_jni_trampoline_ == entry_point);
 }
 
+bool ClassLinker::IsJniDlsymLookupStub(const void* entry_point) const {
+  return entry_point == GetJniDlsymLookupStub();
+}
+
 const void* ClassLinker::GetRuntimeQuickGenericJniStub() const {
   return GetQuickGenericJniStub();
 }