pgsql: Use function attributes for SSE 4.2 even when targeting that ext

Use function attributes for SSE 4.2 even when targeting that extension

On Red Hat 9 systems (or similar), the packaged gcc targets x86-64-v2,
but clang does not. This has caused build failures in the wake of
commit e2809e3a1 when building --with-llvm.

The most expedient fix is to use the same function attributes for
the inlined function as we do for the global function.

Reported-by: Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> (plus members skimmer and bumblebee)
Diagnosed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Tested-by: Todd Cook <cookt(at)blackduck(dot)com>
Discussion: https://postgr.es/m/CANWCAZZSxs3a1YRKehkgk2OHKbrVn+xZ+AWW8Co2R_f70NqqmA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/af0c248557aecb335462d980cb7319bdf85a5c66

Modified Files
--------------
src/include/port/pg_crc32c.h | 6 ++++++
1 file changed, 6 insertions(+)