pgsql: Allow VACUUM to complete faster by avoiding scanning the indexes

Log Message:
-----------
Allow VACUUM to complete faster by avoiding scanning the indexes when no
rows were removed from the heap by the VACUUM.

Simon Riggs

Modified Files:
--------------
    pgsql/src/backend/access/gist:
        gistvacuum.c (r1.11 -> r1.12)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistvacuum.c.diff?r1=1.11&r2=1.12)
    pgsql/src/backend/access/hash:
        hash.c (r1.83 -> r1.84)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/hash/hash.c.diff?r1=1.83&r2=1.84)
    pgsql/src/backend/access/index:
        indexam.c (r1.87 -> r1.88)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/index/indexam.c.diff?r1=1.87&r2=1.88)
    pgsql/src/backend/access/nbtree:
        nbtree.c (r1.136 -> r1.137)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/nbtree.c.diff?r1=1.136&r2=1.137)
    pgsql/src/backend/commands:
        vacuum.c (r1.321 -> r1.322)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuum.c.diff?r1=1.321&r2=1.322)
        vacuumlazy.c (r1.63 -> r1.64)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c.diff?r1=1.63&r2=1.64)
    pgsql/src/include/access:
        genam.h (r1.54 -> r1.55)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/access/genam.h.diff?r1=1.54&r2=1.55)