[SCEV] Skip instrs with non-scevable types in visitAndClearUsers.

No SCEVs are formed for instructions with non-scevable types, so no
other SCEV expressions can depend on them. Skip those instructions and
their users when invalidating SCEV expressions.

Depends on D144847.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D144848