Log Message:
-----------
Be careful to get share lock on each page before computing its free space.
ITAGAKI Takahiro
Modified Files:
--------------
pgsql/contrib/pgstattuple:
pgstattuple.c (r1.30 -> r1.31)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pgstattuple/pgstattuple.c?r1=1.30&r2=1.31)