Recommit "Reorder (shl (add/sub (shl x, C0), y), C1) -> (add/sub (shl x, C0 +...

Recommit "Reorder (shl (add/sub (shl x, C0), y), C1) -> (add/sub (shl x, C0 + C1), (shl y, C1))" 2nd Try

First time caused build failure:
    https://lab.llvm.org/buildbot/#/builders/183/builds/10447
but after investigating it seems to be unrelated. The same
test/build passed later with the original commit here:
    https://lab.llvm.org/buildbot/#/builders/183/builds/10448

This is just expanding the existing pattern that exists for AND/XOR/OR
and gets a bit more parallelism in from the instruction sequence.

Alive2:
Add  - https://alive2.llvm.org/ce/z/dSmPkV
Sub1 - https://alive2.llvm.org/ce/z/6rpi5V
Sub2 - https://alive2.llvm.org/ce/z/UfYeUd

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D141875