Feeder: more efficient solution to memory leak fix

The for loop copies newly created objects into the vector and destroys the original objects. The resize() instantiates the objects directly in the vector. Suggested by Nicolás Alvarez.

sched/feeder.cpp

@@ -560,11 +560,7 @@ void feeder_loop() {
     
     // may need one enumeration per app; create vector
     //
-    for (int i=0; i<napps; i++) {
+    work_items.resize(napps);
-        DB_WORK_ITEM* wi = new DB_WORK_ITEM();
-        work_items.push_back(*wi);
-        delete wi;
-    }
 
     while (1) {
         bool action;