pgsql: Simplify SortSupport for the macaddr data type

Simplify SortSupport for the macaddr data type

As of commit 6aebedc38 Datums are 64-bit values. Since MAC addresses
have only 6 bytes, the abbreviated key always contains the entire
MAC address and is thus authoritative (for practical purposes -- the
tuple sort machinery has no way of knowing that). Abbreviating this
datatype is cheap, and aborting abbreviation prevents optimizations
like radix sort, so remove cardinality estimation.

Author: Aleksander Alekseev <aleksander(at)tigerdata(dot)com>
Reviewed-by: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Suggested-by: John Naylor <johncnaylorls(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAJ7c6TMk10rF_LiMz6j9rRy1rqk-5s+wBPuBefLix4cY+-4s1w@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/30229be755e703cf23fd73e95c5a515f9011cb5a

Modified Files
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src/backend/utils/adt/mac.c | 101 +++-----------------------------------------
1 file changed, 6 insertions(+), 95 deletions(-)