[x86] Simplify vector selection if condition value type matches vselect value...

[x86] Simplify vector selection if condition value type matches vselect value type and true value is all ones or false value is all zeros.
This transformation worked if selector is produced by SETCC, however SETCC is needed only if we consider to swap operands. So I replaced SETCC check for this case.
Added tests for vselect of <X x i1> values.

llvm-svn: 220777