Enhance bool simplifcation in X86 to handle more cases

This patch is revised based on patch from Victor Umansky
<victor.umansky@intel.com>. More cases are handled in X86's bool
simplification, i.e.
- SETCC_CARRY
- value is truncated to i1 with AND

As a by-product, PR5443 is also fixed.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179265 91177308-0d34-0410-b5e6-96231b3b80d8