[php-src] PR #23795: ext/standard: Remove useless _mm_movemask_epi8 check in rot13

Pull Request: https://github.com/php/php-src/pull/23795 Author: LamentXU123 The _mm_movemask_epi8 if-branch seems useless. From comparing, the only possible cases for each byte is 0x00 and 0xFF. So just perform the and and or command anyways is always correct. When the mask aren't all zero, removing them is certainly faster cuz we save a _mm_movemask_epi8 call. When it is all zero, from my limited knowledge I think the [pand](https://uops.info/html-instr/PAND_XMM_XMM.html#MTL-P) and [por](https://uops.info/html-instr/POR_XMM_XMM.html#MTL-P) command is always faster than [pmovmskb](https://uops.info/html-instr/PMOVMSKB_R32_XMM.html#MTL-P). But I might be wrong. I tested this on my personal PC and the improvements are quite stable. ~1.2x-1.3x But note that my env is kind of noisy.