When we generate spill code, then decide we don't need

When we generate spill code, then decide we don't need
to spill after all, we weren't handling 2-instruction
spill sequences correctly (PPC Altivec).  We need to
remove the store in this case.  Removing the other
instruction(s) would be goodness but is not needed for
correctness, and isn't done here.  7331562.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85437 91177308-0d34-0410-b5e6-96231b3b80d8