generic/131: Create server.out manually.

When test generic/131 on nfs, the 'server.out' maybe create
later than expect. Because the server is running on background,
we should ensure the 'server.out' is exist before 'cat' it.

So, let's create the server.out manually.

Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/generic/131

@@ -33,6 +33,9 @@ _require_test_fcntl_advisory_locks
 
 TESTFILE=$TEST_DIR/lock_file
 
+rm -f $TEST_DIR/server.out
+touch $TEST_DIR/server.out
+
 # Start the server
 src/locktest $TESTFILE 2>&1 > $TEST_DIR/server.out &
 locktest_pid1=$!