pgsql: Remove remnants of a JENTRY_ISFIRST flag bit.

Remove remnants of a JENTRY_ISFIRST flag bit.

I removed the flag earlier, but missed a few references in jsonb.h.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/c07693f0c7cde7d269025fe714a124223a189e71

Modified Files
--------------
src/include/utils/jsonb.h |   10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)