[SelectionDAG] Correct the early out in SelectionDAG::getZeroExtendInReg to work properly for vector types.

I don't know if we ever hit this case or not. Turning it into an assert only fired on expanding some atomic operation in a SystemZ lit test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315648 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed