ARM: Remove unnecessary kCoreAlwaysSpillRegister.

The old reasoning behind it is invalid as T32 supports
16-bit instructions that can push/pop a single register.

This reduces the frame size of some methods.

Test: m test-art-host-gtest
Test: aosp_taimen-userdebug boots.
Test: run-gtests.sh
Test: testrunner.py --target --optimizing --32
Change-Id: I35955e4394ca262c0b5d2713b2735ed1f5c99c4a
2 files changed