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
34 files changed