pgsql: Allow pg_monitor to execute pg_current_logfile().

Allow pg_monitor to execute pg_current_logfile().

We allow roles with privileges of pg_monitor to execute functions
like pg_ls_logdir(), so it seems natural that such roles would also
be able to execute this function.

Bumps catversion.

Co-authored-by: Pavlo Golub
Reviewed-by: Daniel Gustafsson
Discussion: https://postgr.es/m/CAK7ymcLmEYWyQkiCZ64WC-HCzXAB0omM%3DYpj9B3rXe8vUAFMqw%40mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8d8afd48d3f298bc4d8ab2b115cc39550132bde7

Modified Files
--------------
doc/src/sgml/func.sgml                       |  5 +++++
src/backend/catalog/system_functions.sql     |  4 ++++
src/include/catalog/catversion.h             |  2 +-
src/test/regress/expected/misc_functions.out | 20 ++++++++++++++++++++
src/test/regress/sql/misc_functions.sql      | 11 +++++++++++
5 files changed, 41 insertions(+), 1 deletion(-)