i386: Handle ZERO_EXTEND like SIGN_EXTEND in bsr patterns [PR120434]

i386: Handle ZERO_EXTEND like SIGN_EXTEND in bsr patterns [PR120434]

The just posted second PR120434 patch causes
+FAIL: gcc.target/i386/pr78103-3.c scan-assembler \\\\m(leaq|addq|incq)\\\\M
+FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\mmovl\\\\M+
+FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\msubq\\\\M
+FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\mxor[lq]\\\\M
While the patch generally improves code generation by often using
ZERO_EXTEND instead of SIGN_EXTEND, where the former is often for free
on x86_64 while the latter requires an extra instruction or larger
instruction than one with just zero extend, the PR78103 combine patterns
and splitters were written only with SIGN_EXTEND in mind.  As CLZ is UB
on 0 and otherwise returns just [0,63] and is xored with 63, ZERO_EXTEND
does the same thing there as SIGN_EXTEND.

2025-06-10  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/120434
	* config/i386/i386.md (*bsr_rex64_2): Rename to ...
	(*bsr_rex64<u>_2): ... this.  Use any_extend instead of sign_extend.
	(*bsr_2): Rename to ...
	(*bsr<u>_2): ... this.  Use any_extend instead of sign_extend.
	(bsr splitters after those): Use any_extend instead of sign_extend.