ObjPtr<>-ify mirror::Class.

And move function definitions that rely on obj_ptr-inl.h
from class.h to class-inl.h .

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 31113334
Change-Id: I5ccc765d0a02b1d37cb39ed68c17b8456faf92ea
diff --git a/openjdkjvmti/ti_heap.cc b/openjdkjvmti/ti_heap.cc
index 01ef4c6..60cb004 100644
--- a/openjdkjvmti/ti_heap.cc
+++ b/openjdkjvmti/ti_heap.cc
@@ -1209,7 +1209,7 @@
       stop_reports_ = !ReportReferenceMaybeEnqueue(JVMTI_HEAP_REFERENCE_CLASS_LOADER,
                                                    nullptr,
                                                    klass,
-                                                   klass->GetClassLoader());
+                                                   klass->GetClassLoader().Ptr());
       if (stop_reports_) {
         return;
       }