Allow redefined intrinsics

We make a change to allow intrinsics to be redefined. Note that
redefined intrinisics will no-longer be optimized as much and will not
be inlined or moved out of loops.

Test: ART_TEST_JIT=true mma -j40 test-art-host

Change-Id: Id6df89bb247d21f7859b48356ceba310eef9d105