i386: Mark XMM4-XMM6 as clobbered by encodekey128/encodekey256
encodekey128 and encodekey256 operations clear XMM4-XMM6. But it is
documented that XMM4-XMM6 are reserved for future usages and software
should not rely upon them being zeroed. Change encodekey128 and
encodekey256 to clobber XMM4-XMM6.
gcc/
PR target/107061
* config/i386/predicates.md (encodekey128_operation): Check
XMM4-XMM6 as clobbered.
(encodekey256_operation): Likewise.
* config/i386/sse.md (encodekey128u32): Clobber XMM4-XMM6.
(encodekey256u32): Likewise.
gcc/testsuite/
PR target/107061
* gcc.target/i386/keylocker-encodekey128.c: Don't check
XMM4-XMM6.
* gcc.target/i386/keylocker-encodekey256.c: Likewise.