JIT: Combine add with shift.

Optimize logical shift for ARM JIT.
Whenever logical shift is followed by an add,
replace it with an add capable of performing
the shift in the same instruction.

This improves performance for usecases
involving code executing in Dalvik.

Change-Id: I3cb807b6d6ef4b053a19e2703676a93a930eb963
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>

Conflicts:
	vm/compiler/codegen/Optimizer.h
	vm/compiler/codegen/arm/LocalOptimizations.cpp
JIT: Use rsb and shift in easy multiply.

For easy multiplication using reverse subtract (when
lit is 2^n-1) use the barrel shifter for rsb.

This improves arithmetic performance for code executing
in Dalvik. E.g String.hashCode.

Change-Id: Ifb086dcec344b30fd3e392ac21d508b43e820cdc
Signed-off-by: Patrik Ryd <patrik.ryd@stericsson.com>

Conflicts:
	vm/compiler/codegen/arm/ArmLIR.h
	vm/compiler/codegen/arm/Assemble.cpp
	vm/compiler/codegen/arm/Thumb/Gen.cpp
	vm/compiler/codegen/arm/Thumb2/Gen.cpp