pgsql: Fix missing rows in query update a=..

Log Message:
-----------
Fix missing rows in query
update a=.. where a... with GiST index on column 'a'

Tags:
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REL8_0_STABLE

Modified Files:
--------------
pgsql/src/backend/access/gist:
gist.c (r1.112 -> r1.112.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gist.c.diff?r1=1.112&r2=1.112.4.1)
gistget.c (r1.43 -> r1.43.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistget.c.diff?r1=1.43&r2=1.43.4.1)
gistscan.c (r1.56 -> r1.56.4.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistscan.c.diff?r1=1.56&r2=1.56.4.1)