Add some enumeration commas, for consistency

src/backend/access/gist/gistbuild.c

src/backend/commands/async.c

src/backend/commands/tablecmds.c

src/backend/libpq/hba.c

src/backend/utils/adt/float.c

src/backend/utils/adt/numeric.c

src/backend/utils/misc/guc.c

src/bin/pg_basebackup/pg_basebackup.c

src/bin/pg_dump/pg_dump.c

src/bin/pg_dump/pg_restore.c

src/test/regress/expected/numeric.out