Remove a few more bogus returns when the switch covers all the
enumerators.

Also remove a default that led to llvm_unreachable to make another
switch warn if any enumerators fail to be covered.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130646 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed