pgsql: Remove trailing commas in enums.

Remove trailing commas in enums.

These aren't valid C89. Found thanks to gcc's -Wc90-c99-compat. These
exist in differing places in most supported branches.

Branch
------
REL9_3_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/f1d26d3e0a7f0e1928cfb672c6c56fc342174a58

Modified Files
--------------
src/backend/access/transam/xlog.c  | 2 +-
src/include/catalog/objectaccess.h | 2 +-
src/include/pgstat.h               | 2 +-
src/include/utils/jsonapi.h        | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)