pgsql: Get rid of explicit argument-count markings in tab-complete.c.

Get rid of explicit argument-count markings in tab-complete.c.

This replaces the "TailMatchesN" macros with just "TailMatches",
and likewise "HeadMatchesN" becomes "HeadMatches" and "MatchesN"
becomes "Matches". The various COMPLETE_WITH_LISTn macros are
reduced to COMPLETE_WITH, and the single-item COMPLETE_WITH_CONST
also gets folded into that. This eliminates a lot of minor
annoyance in writing tab-completion rules. Usefully, the compiled
code also gets a bit smaller (10% or so, on my machine).

The implementation depends on variadic macros, so we couldn't have
done this before we required C99.

Andres Freund and Thomas Munro; some cosmetic cleanup by me.

Discussion: https://postgr.es/m/d8jo9djvm7h.fsf@dalvik.ping.uio.no

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/4f3b38fe2bde72d59b7eab593ff72e0cebd9ecc6

Modified Files
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src/bin/psql/tab-complete.c | 2551 ++++++++++++++++++++-----------------------
src/include/c.h | 33 +
2 files changed, 1222 insertions(+), 1362 deletions(-)