combine.c (try_widen_shift_mode): Factor out code to check if an integer constant is a low-order bitmask from here ...

	* combine.c (try_widen_shift_mode): Factor out code to check if an
        integer constant is a low-order bitmask from here ...
	* rtlanal.c (low_bitmask_len): ... to here.
	* rtl.h (low_bitmask_len): Declare.

From-SVN: r150656