Two changes:

1. Switch expression and cases are compared signed and are sign extended.
2. For function results needing extended, do SIGN_EXTEND if the SExtAttribute
   is set and ZERO_EXTEND if the ZExtAttribute is set, otherwise just let
   the Legalizer do ANY_EXTEND.
This fixes the recent regression in kimwitu++ and probably the llvm-gcc
bootstrap issue we had today.

llvm-svn: 32830