PR middle-end/49489
	* builtins.c (expand_builtin_unop): Call expand_unop with 0 as
	unsignedp argument instead of 1 for clrsb_optab.
	(fold_builtin_bitop): Fix masking for width > HOST_BITS_PER_WIDE_INT
	and < 2 * HOST_BITS_PER_WIDE_INT.  Optimize BUILT_IN_CLRSB*.
	(fold_builtin_1): Call fold_builtin_binop for BUILT_IN_CLRSB*.
	* optabs.c (widen_leading): Call widen_operand and expand_unop
	with 0 as unsignedp argument instead of 1 for clrsb_optab.
	(expand_unop): Subtract difference of mode sizes also for
	clrsb_optab.

From-SVN: r175265