apply no-mpi changes to posix module

darshan-runtime/darshan.h

@@ -88,6 +88,7 @@
  * avoid any reduction steps.
  */
 typedef void (*darshan_module_redux)(
+    void *mod_buf, /* input parameter indicating module's buffer address */
     MPI_Comm mod_comm,  /* MPI communicator to run collectives with */
     darshan_record_id *shared_recs, /* list of shared data record ids */
     int shared_rec_count /* count of shared data records */

darshan-runtime/lib/darshan-core.c

@@ -563,8 +563,9 @@ void darshan_core_shutdown()
             }
 
             /* allow the module an opportunity to reduce shared files */
-            if(this_mod->mod_funcs.mod_redux_func)
-                this_mod->mod_funcs.mod_redux_func(MPI_COMM_WORLD, mod_shared_recs,
+            if(this_mod->mod_funcs.mod_redux_func && (mod_shared_recs > 0) &&
+               (!getenv("DARSHAN_DISABLE_SHARED_REDUCTION")))
+                this_mod->mod_funcs.mod_redux_func(mod_buf, MPI_COMM_WORLD, mod_shared_recs,
                     mod_shared_rec_cnt); 
         }
 #endif