i386: Improve SImode constant - __builtin_clzll for -mno-lzcnt

i386: Improve SImode constant - __builtin_clzll for -mno-lzcnt

Add a zero_extend patten for bsr_rex64_1 and use it to split SImode
constant - __builtin_clzll to avoid unncessary zero_extend.

gcc/

	PR target/78103
	* config/i386/i386.md (bsr_rex64_1_zext): New.
	(combine splitter for constant - clzll): Replace gen_bsr_rex64_1
	with gen_bsr_rex64_1_zext.

gcc/testsuite/

	PR target/78103
	* gcc.target/i386/pr78103-2.c: Also scan incl.
	* gcc.target/i386/pr78103-3.c: Scan leal|addl|incl for x32.  Also
	scan incq.