pgsql: Fix missed case for builtin collation provider.

Fix missed case for builtin collation provider.

A missed check for the builtin collation provider could result in
falling through to call isalpha().

This does not appear to have practical consequences because it only
happens for characters in the ASCII range. Regardless, the builtin
provider should not be calling libc functions, so backpatch.

Discussion: https://postgr.es/m/1bd5a0a5192f82c22ee7527e825b18ab0028b2c7.camel@j-davis.com
Backpatch-through: 17

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/ff33df26c2446107a20e3432b4c73850536678b9

Modified Files
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src/backend/utils/adt/like_support.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)