gallivm: enable stores of integer types. (v2) + fix ARL

gallivm: enable stores of integer types. (v2) + fix ARL

Infer from the operand the type of value to store.
MOV is untyped but we use the float store path.

v2: make MOV use float store path.

I've had to squash merge the ARL fix to be stored
as an integer in here to avoid regressions in a number
of piglit tests.

From now on ARL stores to an integer just like HW does.

Signed-off-by: Dave Airlie <airlied@redhat.com>