python - be: Add ugly CPP to allow _compilation_ against 8.1devel.

Log Message:
-----------
Add ugly CPP to allow _compilation_ against 8.1devel. This fails to address the
issue of the Array friendly oidvectors; as namespace.c/ns_function depends on
the old style, so just #if it out for now.

pg_config.h is actually included by c.h in both 8.0 and 8.1, but the issue of a
redef only showed when compiled against 8.1.
New heap_tuplemodify takes a TupleDesc now.
Changes in TupleTableSlot and DestReceiver causes a number of changes in Portal.

Use new static system RelationId's instead of RelationSysNameGetRelation.
A better way to handle this difference might be to setup some argument-less
macros which map to the appropriate call for each version; should look a lot
better than those #if's sprinkled about.

(No official support for 8.1 ;)

Modified Files:
--------------
be/include/pypg:
postgres.h (r1.4 -> r1.5)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/include/pypg/postgres.h.diff?r1=1.4&r2=1.5)
be/src:
call.c (r1.4 -> r1.5)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/call.c.diff?r1=1.4&r2=1.5)
constants.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/constants.c.diff?r1=1.5&r2=1.6)
error.c (r1.6 -> r1.7)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/error.c.diff?r1=1.6&r2=1.7)
function.c (r1.4 -> r1.5)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/function.c.diff?r1=1.4&r2=1.5)
module.c (r1.12 -> r1.13)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/module.c.diff?r1=1.12&r2=1.13)
namespace.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/namespace.c.diff?r1=1.3&r2=1.4)
pl.c (r1.11 -> r1.12)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/pl.c.diff?r1=1.11&r2=1.12)
query.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/query.c.diff?r1=1.3&r2=1.4)
relation.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/relation.c.diff?r1=1.3&r2=1.4)
savepoint.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/savepoint.c.diff?r1=1.3&r2=1.4)
tif.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/tif.c.diff?r1=1.5&r2=1.6)
transaction.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/transaction.c.diff?r1=1.5&r2=1.6)
utils.c (r1.7 -> r1.8)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/utils.c.diff?r1=1.7&r2=1.8)
be/src/call:
function.c (r1.3 -> r1.4)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/call/function.c.diff?r1=1.3&r2=1.4)
pl.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/call/pl.c.diff?r1=1.5&r2=1.6)
portal.c (r1.2 -> r1.3)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/call/portal.c.diff?r1=1.2&r2=1.3)
trigger.c (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/call/trigger.c.diff?r1=1.5&r2=1.6)