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.

llvm-svn: 179265