pgsql: Prevent creating window functions with default arguments.

Prevent creating window functions with default arguments.

Insertion of default arguments doesn't work for window functions, which is
likely to cause a crash at runtime if the implementation code doesn't check
the number of actual arguments carefully.  It doesn't seem worth working
harder than this for pre-9.2 branches.

Branch
------
REL8_4_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/72c8a584bf7dd362227a3e0c23c39cc217f5753d

Modified Files
--------------
src/backend/catalog/pg_proc.c |    6 ++++++
1 file changed, 6 insertions(+)