JIT: Hoist loop load operations above loop.

Hoists Dalvik frame load operations outside of loops, when possible.
This improves performance in most loops, and is noticable in many
applications.

Change-Id: Ibe42b509b50a13f19758fd923f31d703e33a51c6
Signed-off-by: Henrik Smiding <henrik.smiding@stericsson.com>
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>

Conflicts:
	vm/compiler/Loop.h