pgsql: Remove pg_regex_collation

Remove pg_regex_collation

We can also use the existing pg_regex_locale as the cache key, which
is the only use of this variable.

Reviewed-by: Jeff Davis <pgsql@j-davis.com>
Discussion: https://www.postgresql.org/message-id/flat/b1b92ae1-2e06-4619-a87a-4b4858e547ec%40eisentraut.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/792b2c7e6d926e61e8ff3b33d3e22d7d74e7a437

Modified Files
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src/backend/regex/regc_pg_locale.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)