[COMMITTERS] pgsql: Comment fixes for extended statistics

Comment fixes for extended statistics

Clean up some code comments in new extended statistics code, from
7b504eb282.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/b1fc51a36ecdf854be9e41ffb99953c40ef96ccf

Modified Files
--------------
src/backend/optimizer/util/plancat.c    | 1 +
src/backend/statistics/dependencies.c   | 9 +++++++--
src/backend/statistics/extended_stats.c | 7 ++++---
src/backend/utils/cache/relcache.c      | 1 -
src/include/nodes/relation.h            | 8 +++-----
5 files changed, 15 insertions(+), 11 deletions(-)