pgsql: Make consistent a couple of log messages when parsing HBA files

Make consistent a couple of log messages when parsing HBA files

This commit adjusts two log messages:
- When a field in pg_ident.conf is not populated, report the line of the
configuration file in an error context message instead of the main
entry.
- When parsing pg_ident.conf and finding an invalid regexp, add some
information about the line of the configuration file involved within an
error context message.

Author: Julien Rouhaud
Discussion: https://postgr.es/m/20220223045959.35ipdsvbxcstrhya@jrouhaud

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/718fe0a14add0fadb17d715d7aa24ebcf3fb35c4

Modified Files
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src/backend/libpq/hba.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)