pgsql: Allow pg_locale_t APIs to work when ctype_is_c.

Allow pg_locale_t APIs to work when ctype_is_c.

Previously, the caller needed to check ctype_is_c first for some
routines and not others. Now, the APIs consistently work, and the
caller can just check ctype_is_c for optimization purposes.

Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
Reviewed-by: Chao Li <li.evan.chao@gmail.com>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/147602822597204aa436415ebe295926b268ab5c

Modified Files
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src/backend/utils/adt/pg_locale.c      | 82 +++++++++++++++++++++++++++++++---
src/backend/utils/adt/pg_locale_libc.c |  6 +++
2 files changed, 82 insertions(+), 6 deletions(-)