pgsql: Revert patch, doesn't do what it should: * %Disallow changing

Log Message:
-----------
Revert patch, doesn't do what it should:

* %Disallow changing default expression of a SERIAL column

Dhanaraj M

Modified Files:
--------------
pgsql/doc:
TODO (r1.1904 -> r1.1905)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.1904&r2=1.1905)
pgsql/doc/src/FAQ:
TODO.html (r1.407 -> r1.408)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.407&r2=1.408)
pgsql/src/backend/catalog:
dependency.c (r1.55 -> r1.56)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/dependency.c.diff?r1=1.55&r2=1.56)
heap.c (r1.300 -> r1.301)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/heap.c.diff?r1=1.300&r2=1.301)
pgsql/src/backend/commands:
tablecmds.c (r1.187 -> r1.188)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablecmds.c.diff?r1=1.187&r2=1.188)
pgsql/src/include/catalog:
dependency.h (r1.24 -> r1.25)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/dependency.h.diff?r1=1.24&r2=1.25)
heap.h (r1.81 -> r1.82)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/heap.h.diff?r1=1.81&r2=1.82)