[SelectionDAG] Use WidenTargetBoolean in WidenVecRes_MLOAD and...

[SelectionDAG] Use WidenTargetBoolean in WidenVecRes_MLOAD and WidenVecOp_MSTORE instead of implementing it manually and incorrectly.

The CONCAT_VECTORS operand get its type from getSetCCResultType, but if the mask type and the setcc have different scalar sizes this creates an illegal CONCAT_VECTORS operation. The concat type should be 2x the mask type, and then an extend should be added if needed.

llvm-svn: 319744