pgsql: Trivial patch to double vacuum speed on tables with no indexes

Log Message:
-----------
Trivial patch to double vacuum speed on tables with no indexes (prevent
second scan of table).

Gregory Stark

Modified Files:
--------------
pgsql/src/backend/commands:
vacuumlazy.c (r1.76 -> r1.77)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/vacuumlazy.c.diff?r1=1.76&r2=1.77)