pgsql: Fix a bunch of bad interactions between partial indexes and the

Log Message:
-----------
Fix a bunch of bad interactions between partial indexes and the new
planning logic for bitmap indexscans.  Partial indexes create corner
cases in which a scan might be done with no explicit index qual conditions,
and the code wasn't handling those cases nicely.  Also be a little
tenser about eliminating redundant clauses in the generated plan.
Per report from Dmitry Karasik.

Modified Files:
--------------
    pgsql/src/backend/nodes:
        list.c (r1.64 -> r1.65)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/list.c.diff?r1=1.64&r2=1.65)
    pgsql/src/backend/optimizer/path:
        indxpath.c (r1.186 -> r1.187)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/indxpath.c.diff?r1=1.186&r2=1.187)
        orindxpath.c (r1.73 -> r1.74)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/path/orindxpath.c.diff?r1=1.73&r2=1.74)
    pgsql/src/backend/optimizer/plan:
        createplan.c (r1.195 -> r1.196)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/createplan.c.diff?r1=1.195&r2=1.196)
        planagg.c (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/plan/planagg.c.diff?r1=1.6&r2=1.7)
    pgsql/src/backend/optimizer/util:
        restrictinfo.c (r1.38 -> r1.39)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/optimizer/util/restrictinfo.c.diff?r1=1.38&r2=1.39)
    pgsql/src/include/nodes:
        pg_list.h (r1.51 -> r1.52)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/pg_list.h.diff?r1=1.51&r2=1.52)
    pgsql/src/include/optimizer:
        paths.h (r1.85 -> r1.86)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/paths.h.diff?r1=1.85&r2=1.86)
        restrictinfo.h (r1.32 -> r1.33)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/optimizer/restrictinfo.h.diff?r1=1.32&r2=1.33)