ART: Fix ARM64 long-jump context caller-save smashes

In aarch64, d8-d15 are callee-saved. We smashed exactly the wrong
registers.

Add code to stub_test that checks whether the callee-saved fp
registers are preserved on ARM64. There are no callee-saved registers
for x86, so the invoke methods are not extended for those architectures.

Fix a minor type in callee-save frame setup for ARM64.

Bug: 14160872
Change-Id: I080fce6eda7d560b4efb610f0e9454f3471fa4f9