Improved DCA transfer function for Shl.
Fixed and improved DCA transfer function for Shr(s).

Before, the transfer function for Shrs was wrong for unsigned modes.
Improved constant bits transfer function for Shl.
Improved constant bits transfer function for Shr.
Improved constant bits transfer function for Shrs.
Fixed mode of modulo-shift mask.

So far, we create care information with the wrong mode.
Thus, the care_for function conservatively mark all bits as relevant.