pgsql: Add a 'waiting' column to pg_stat_activity to carry the same

Log Message:
-----------
Add a 'waiting' column to pg_stat_activity to carry the same information
that ps_status provides by appending 'waiting' to the PS display.  This
completes the project of making it feasible to turn off process title
updates and instead rely on pg_stat_activity.  Per my suggestion a few
weeks ago.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        monitoring.sgml (r1.36 -> r1.37)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/monitoring.sgml.diff?r1=1.36&r2=1.37)
    pgsql/src/backend/catalog:
        system_views.sql (r1.29 -> r1.30)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/system_views.sql.diff?r1=1.29&r2=1.30)
    pgsql/src/backend/postmaster:
        pgstat.c (r1.136 -> r1.137)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c.diff?r1=1.136&r2=1.137)
    pgsql/src/backend/storage/lmgr:
        lock.c (r1.170 -> r1.171)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/lock.c.diff?r1=1.170&r2=1.171)
    pgsql/src/backend/utils/adt:
        pgstatfuncs.c (r1.32 -> r1.33)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/pgstatfuncs.c.diff?r1=1.32&r2=1.33)
    pgsql/src/include/catalog:
        catversion.h (r1.350 -> r1.351)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.350&r2=1.351)
        pg_proc.h (r1.421 -> r1.422)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.421&r2=1.422)
    pgsql/src/include:
        pgstat.h (r1.48 -> r1.49)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pgstat.h.diff?r1=1.48&r2=1.49)
    pgsql/src/test/regress/expected:
        rules.out (r1.117 -> r1.118)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/rules.out.diff?r1=1.117&r2=1.118)