StructurizeCFG: fix inverting conditions
Author: Samuel Pitoiset
Without this patch, it appears to me that we are selecting
the wrong operand when inverting conditions. In the attached
test, it will select %tmp3 instead of %tmp4. To fix it, just
use 'A' as everywhere.
This fixes a regression introduced by
"[PatternMatch] define m_Not using m_Xor and cst_pred_ty"