patch 7.4.1501

Problem:    Garbage collection with an option channel is not tested.
Solution:   Call garbagecollect() in the test.

src/version.c

@@ -743,6 +743,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1501,
 /**/
     1500,
 /**/