pgsql: Fix comments of output routines for pg_ndistinct and pg_dependen

Fix comments of output routines for pg_ndistinct and pg_dependencies

Oversights in 7b504eb282ca (for pg_ndistinct) and 2686ee1b7ccf (for
pg_dependencies).

Reported-by: Man Zeng <zengman@halodbtech.com>
Discussion: https://postgr.es/m/176293711658.2081918.12019224686811870203.pgcf@coridan.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/040a39ed25bf8480bbd1947a2edeb0167f1e0789

Modified Files
--------------
src/backend/utils/adt/pg_dependencies.c | 2 +-
src/backend/utils/adt/pg_ndistinct.c    | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)