broker: reduce scope of some modhash funcs

Problem: modhash_add() and modhash_remove() are now only used
internally in modhash.c, yet they have global scope.

Declare them static.

Author: garlick

src/broker/modhash.c

@@ -57,7 +57,7 @@ int modhash_response_sendmsg_new (modhash_t *mh, flux_msg_t **msg)
     return module_sendmsg_new (p, msg);
 }
 
-void modhash_add (modhash_t *mh, module_t *p)
+static void modhash_add (modhash_t *mh, module_t *p)
 {
     int rc;
 
@@ -68,7 +68,7 @@ void modhash_add (modhash_t *mh, module_t *p)
                   (zhash_free_fn *)module_destroy);
 }
 
-void modhash_remove (modhash_t *mh, module_t *p)
+static void modhash_remove (modhash_t *mh, module_t *p)
 {
     zhash_delete (mh->zh_byuuid, module_get_uuid (p));
 }

src/broker/modhash.h

@@ -28,9 +28,6 @@ typedef struct modhash modhash_t;
 modhash_t *modhash_create (struct broker *ctx);
 int modhash_destroy (modhash_t *mh);
 
-void modhash_add (modhash_t *mh, module_t *p);
-void modhash_remove (modhash_t *mh, module_t *p);
-
 /* Send an event message to all modules that have matching subscription.
  */
 int modhash_event_mcast (modhash_t *mh, const flux_msg_t *msg);