pgsql-server: Fix problems in pg_autovacuum: 1) temp table crash 2)

Log Message:
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Fix problems in pg_autovacuum:

1) temp table crash

2) Check send_query() function call return value.

Backpatch to 7.4.X.

Tags:
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REL7_4_STABLE

Modified Files:
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pgsql-server/contrib/pg_autovacuum:
pg_autovacuum.c (r1.8.2.7 -> r1.8.2.8)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/contrib/pg_autovacuum/pg_autovacuum.c.diff?r1=1.8.2.7&r2=1.8.2.8)
pg_autovacuum.h (r1.7.2.2 -> r1.7.2.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/contrib/pg_autovacuum/pg_autovacuum.h.diff?r1=1.7.2.2&r2=1.7.2.3)