[LICM] Allow promotion with non-load/store users

If there are non-load/store users of the promoted pointer, we
currently abort promotion. However, having such users isn't really
relevant to the transform. We already separately check that a)
there are no instructions that modref the promoted pointer and
b) that a pointer capture disables store promotion.

In the affected @test_captured_in_loop test case we have a readnone
capture of the promoted pointer, which means that load promotion
can be performed (while store promotion cannot).

Differential Revision: https://reviews.llvm.org/D133485