pgsql: Fix pg_crc32c_armv8_choose.c to build with ancient glibc release

Fix pg_crc32c_armv8_choose.c to build with ancient glibc releases.

If you go back as far as the RHEL7 era, <sys/auxv.h> does not provide
the HWCAPxxx macros needed with elf_aux_info or getauxval, so you need
to get those from the kernel header <asm/hwcap.h> instead. We knew
that for the 32-bit case but failed to extrapolate to the 64-bit case.
Oversight in commit aac831caf.

Reported-by: GaoZengqi <pgf00a(at)gmail(dot)com>
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/CAFmBtr3Av62-jBzdhFkDHXJF9vQmNtSnH2upwODjnRcsgdTytw@mail.gmail.com
Backpatch-through: 18

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/db4eba15266e4f78aa62fd1444f3e858a284c686

Modified Files
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src/port/pg_crc32c_armv8_choose.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)