Implement getrusage

Implement getrusage.
These fields of struct rusage are not supported and always set to zero at this time
long ru_nswap;           /* swaps */
long ru_inblock;         /* block input operations */
long ru_oublock;         /* block output operations */
long ru_msgsnd;          /* messages sent */
long ru_msgrcv;          /* messages received */
long ru_nvcsw;           /* voluntary context switches */
long ru_nivcsw;          /* involuntary context switches */

test75.c is the unit test for this new function

Change-Id: I3f1eb69de1fce90d087d76773b09021fc6106539

kernel/proc.c

@@ -1906,3 +1906,8 @@ void ser_dump_proc()
                 print_proc_recursive(pp);
         }
 }
+
+void increase_proc_signals(struct proc *p)
+{
+	p->p_signal_received++;
+}