pgsql: pg_stat_{ssl,gssapi}: Show only processes with connections

pg_stat_{ssl,gssapi}: Show only processes with connections

It is pointless to show in those views auxiliary processes that don't
open network connections.

A small incompatibility is that anybody joining pg_stat_activity and
pg_stat_ssl/pg_stat_gssapi will have to use a left join if they want to
see such auxiliary processes.

Author: Euler Taveira
Discussion: https://postgr.es/m/20190904151535.GA29108@alvherre.pgsql

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5c46e7d82e88859395c2688c37bb643ae7dbbfa1

Modified Files
--------------
src/backend/catalog/system_views.sql | 6 ++++--
src/include/catalog/catversion.h     | 2 +-
src/test/regress/expected/rules.out  | 6 ++++--
3 files changed, 9 insertions(+), 5 deletions(-)