optabs.c: Remove unnecessary forward declarations.

optabs.c: Remove unnecessary forward declarations.

	* optabs.c: Remove unnecessary forward declarations.
	(expand_unop_direct): New, broken out of expand_unop.
	(expand_doubleword_clz): New.
	(expand_ctz): Move above expand_ffs.  Use
	start_sequence, end_sequence, add_equal_note, and
	expand_unop_direct.  Add more commentary.
	(expand_ffs): Try both ctz optab and expand_ctz.
	Generate a test and branch if the hardware doesn't give us
	a useful value for input zero.  Style improvements similar to
	expand_ctz.

	* config/arm/arm.md (ffssi2, ctzsi2): Delete.

From-SVN: r128054