pgsql: Add missing check_collation_set call to bpcharne().

Add missing check_collation_set call to bpcharne().

We should throw an error for indeterminate collation, but bpcharne()
was missing that logic, resulting in a much less user-friendly error
(either an assertion failure or "cache lookup failed for collation 0").

Per report from Manuel Rigger.  Back-patch to v12 where the mistake
came in, evidently in commit 5e1963fb7.  (Before non-deterministic
collations, this function wasn't collation sensitive.)

Discussion: https://postgr.es/m/CA+u7OA4HOjtymxAbuGNh4-X_2R0Lw5n01tzvP8E5-i-2gQXYWA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d57d61533a2b5b27b60cc9024c54688390871bf6

Modified Files
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src/backend/utils/adt/varchar.c | 2 ++
1 file changed, 2 insertions(+)