pgsql: Simple constraint exclusion.

Log Message:
-----------
Simple constraint exclusion. For now, only child tables of inheritance
scans are candidates for exclusion; this should be fixed eventually.
Simon Riggs, with some help from Tom Lane.

Modified Files:
--------------
pgsql/doc/src/sgml:
runtime.sgml (r1.338 -> r1.339)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/runtime.sgml.diff?r1=1.338&r2=1.339)
pgsql/src/backend/optimizer/path:
allpaths.c (r1.134 -> r1.135)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/allpaths.c.diff?r1=1.134&r2=1.135)
pgsql/src/backend/optimizer/plan:
createplan.c (r1.194 -> r1.195)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/createplan.c.diff?r1=1.194&r2=1.195)
planagg.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planagg.c.diff?r1=1.5&r2=1.6)
pgsql/src/backend/optimizer/util:
plancat.c (r1.112 -> r1.113)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/plancat.c.diff?r1=1.112&r2=1.113)
predtest.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/predtest.c.diff?r1=1.1&r2=1.2)
pgsql/src/backend/utils/misc:
guc.c (r1.276 -> r1.277)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.276&r2=1.277)
postgresql.conf.sample (r1.153 -> r1.154)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/postgresql.conf.sample.diff?r1=1.153&r2=1.154)
pgsql/src/bin/psql:
tab-complete.c (r1.133 -> r1.134)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/tab-complete.c.diff?r1=1.133&r2=1.134)
pgsql/src/include/nodes:
relation.h (r1.116 -> r1.117)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/relation.h.diff?r1=1.116&r2=1.117)
pgsql/src/include/optimizer:
cost.h (r1.68 -> r1.69)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/cost.h.diff?r1=1.68&r2=1.69)
plancat.h (r1.36 -> r1.37)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/plancat.h.diff?r1=1.36&r2=1.37)
predtest.h (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/predtest.h.diff?r1=1.1&r2=1.2)
pgsql/src/test/regress/expected:
rangefuncs.out (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rangefuncs.out.diff?r1=1.11&r2=1.12)