librlist: expose rlist_copy_internal() in rlist_private.h

Problem: rlist_copy_internal() is declared static which means all
copy implementations must be defined directly in rlist.c.

Expose rlist_copy_internal() in rlist_private.h to allow copy
implementations to be placed in separate source files.

Author: grondo

src/common/librlist/rlist.c

@@ -214,11 +214,9 @@ int rlist_add_rnode (struct rlist *rl, struct rnode *n)
     return 0;
 }
 
-typedef struct rnode * (*rnode_copy_f) (const struct rnode *, void *arg);
-
-static struct rlist *rlist_copy_internal (const struct rlist *orig,
-                                          rnode_copy_f cpfn,
-                                          void *arg)
+struct rlist *rlist_copy_internal (const struct rlist *orig,
+                                   rnode_copy_f cpfn,
+                                   void *arg)
 {
     struct rnode *n;
     struct rlist *rl = rlist_create ();

src/common/librlist/rlist_private.h

@@ -13,4 +13,10 @@
 
 int rlist_add_rnode (struct rlist *rl, struct rnode *n);
 
+typedef struct rnode * (*rnode_copy_f) (const struct rnode *, void *arg);
+
+struct rlist *rlist_copy_internal (const struct rlist *orig,
+                                   rnode_copy_f cpfn,
+                                   void *arg);
+
 #endif /* !HAVE_SCHED_RLIST_PRIVATE_H */