ART: Use StackReference in Quick Stack Frame

The method reference at the bottom of a quick frame is a stack
reference and not a native pointer. This is important for 64b
architectures, where the notions do not coincide.

Change key methods to have StackReference<mirror::ArtMethod>*
parameter instead of mirror::ArtMethod**. Make changes to
invoke stubs for 64b archs, change the frame setup for JNI code
(both generic JNI and compilers), tie up loose ends.

Tested on x86 and x86-64 with host tests. On x86-64, tests succeed
with jni compiler activated. x86-64 QCG was not tested.

Tested on ARM32 with device tests.

Fix ARM64 not saving x19 (used for wSUSPEND) on upcalls.

Tested on ARM64 in interpreter-only + generic-jni mode.

Fix ARM64 JNI Compiler to work with the CL.

Tested on ARM64 in interpreter-only + jni compiler.

Change-Id: I77931a0cbadd04d163b3eb8d6f6a6f8740578f13