pg_upgrade: preserve freeze info for postgres/template1 dbs

pg_database.datfrozenxid and pg_database.datminmxid were not preserved
for the 'postgres' and 'template1' databases.  This could cause missing
clog file errors on access to user tables and indexes after upgrades in
these databases.

Backpatch through 9.0

src/bin/pg_dump/pg_dumpall.c

@@ -1416,6 +1416,7 @@ dumpCreateDB(PGconn *conn)
 								  dbconnlimit);
 
 			appendPQExpBufferStr(buf, ";\n");
+		}
 
 		if (binary_upgrade)
 		{
@@ -1427,7 +1428,6 @@ dumpCreateDB(PGconn *conn)
 			appendStringLiteralConn(buf, dbname, conn);
 			appendPQExpBufferStr(buf, ";\n");
 		}
-		}
 
 		if (!skip_acls &&
 			!buildACLCommands(fdbname, NULL, "DATABASE", dbacl, dbowner,