nir/loop_analyze: Track induction variables incremented by more operations

nir/loop_analyze: Track induction variables incremented by more operations

These operations are covered:

 - imul
 - fmul
 - ishl
 - ishr
 - ushr

The only cases that can be currently affected are those where the
calculated loop-trip count would be zero.

v2 (idr): Split out from original commit. Rebase on lots of other work.

v3 (idr): Move operand size assertion. This code only cares that the
operands have the same size for the iadd and fadd cases. In other
cases, such as shifts, the sizes may not match. Fixes assertion
failures in
tests/spec/arb_gpu_shader_int64/glsl-fs-loop-unroll-ishl-int64.shader_test.

No shader-db or fossil-db changes on any Intel platform.

Signed-off-by: Yevhenii Kolesnikov <yevhenii.kolesnikov@globallogic.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3445>