pgsql: Allow GRANT on pg_log_backend_memory_contexts().

Allow GRANT on pg_log_backend_memory_contexts().

Remove superuser check, allowing any user granted permissions on
pg_log_backend_memory_contexts() to log the memory contexts of any
backend.

Note that this could allow a privileged non-superuser to log the
memory contexts of a superuser backend, but as discussed, that does
not seem to be a problem.

Reviewed-by: Nathan Bossart, Bharath Rupireddy, Michael Paquier, Kyotaro Horiguchi, Andres Freund
Discussion: https://postgr.es/m/e5cf6684d17c8d1ef4904ae248605ccd6da03e72.camel@j-davis.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f0b051e322d530a340e62f2ae16d99acdbcb3d05

Modified Files
--------------
doc/src/sgml/func.sgml | 1 -
src/backend/catalog/system_functions.sql | 2 ++
src/backend/utils/adt/mcxtfuncs.c | 14 ++++--------
src/include/catalog/catversion.h | 2 +-
src/test/regress/expected/misc_functions.out | 33 ++++++++++++++++++++++++++--
src/test/regress/sql/misc_functions.sql | 26 ++++++++++++++++++++--
6 files changed, 62 insertions(+), 16 deletions(-)