Avoid undefined behavior in a way that doesn’t require
the input buffer to be aligned.
From a suggestion by Lasse Collin in:
https://lists.gnu.org/r/bug-gnulib/2025-01/msg00148.html
* lib/crc-x86_64-pclmul.c (crc32_update_no_xor_pclmul):
Since the const void * pointer ‘buf’ might not be aligned,
assign it to const __m128i_u * instead of to const __m128i *.
* lib/crc.c (crc32_update_no_xor):
Remove recently-addeda check for buffer alignment.