patch 7.4.1719

Problem:    Leaking memory when there is a cycle involving a job and a
            partial.
Solution:   Add a copyID to job and channel.  Set references in items referred
            by them.  Go through all jobs and channels to find unreferenced
            items.  Also, decrement reference counts when garbage collecting.

src/globals.h

@@ -1619,6 +1619,8 @@ EXTERN int  alloc_fail_countdown INIT(= -1);
 EXTERN int  alloc_fail_repeat INIT(= 0);
 
 EXTERN int  disable_char_avail_for_testing INIT(= 0);
+
+EXTERN int  in_free_unref_items INIT(= FALSE);
 #endif
 
 /*