Teach the table generated emitPseudoExpansionLowering function to not emit a switch statement containing only a default statement (and no cases). Updated some of the code to use range-based for loops as well. No functional changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209521 91177308-0d34-0410-b5e6-96231b3b80d8