IR: Simplify replaceOperandWith(), NFC

This will call `handleChangedOperand()` less frequently, but in that
case (i.e., `isStoredDistinctInContext()`) it has identical logic to
here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225643 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed