pgsql: Use ARM Advanced SIMD (NEON) intrinsics where available

Use ARM Advanced SIMD (NEON) intrinsics where available

NEON support is required on the Aarch64 architecture for standard
implementations. Hardware designers for specialized markets can choose
not to support it, but that's true of floating point as well, which
we assume is supported. As with x86, some SIMD support is available
on 32-bit platforms, but those are not interesting from a performance
standpoint and would require an inconvenient runtime check.

Nathan Bossart

Reviewed by John Naylor, Andres Freund, Thomas Munro, and Tom Lane
Discussion: https://www.postgresql.org/message-id/flat/CAFBsxsEyR9JkfbPcDXBRYEfdfC__OkwVGdwEAgY4Rv0cvw35EA%40mail.gmail.com#aba7a64b11503494ffd8dd27067626a9

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/82739d4a80f2eeb2f96b56477bb04e463ea24800

Modified Files
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src/include/port/simd.h | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)