pgsql: Reverting previous commit, pending investigation

Reverting previous commit, pending investigation
of sporadic seg faults from various build farm members.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/4f14c86d7434376b95477aeeb07fcc7272f4c47d

Modified Files
--------------
doc/src/sgml/ref/alter_table.sgml         |   11 ---
src/backend/commands/tablecmds.c          |  138 -----------------------------
src/backend/parser/gram.y                 |   15 ----
src/include/nodes/parsenodes.h            |    1 -
src/test/regress/expected/foreign_key.out |   19 ----
src/test/regress/sql/foreign_key.sql      |   20 -----
6 files changed, 204 deletions(-)