tests: msg_send_receive: fix "sent ptr goes out of scope" bug

tests/msg_send_receive/main.c

@@ -37,23 +37,26 @@ static char thread2_stack[THREAD2_STACKSIZE];
 
 static kernel_pid_t thread1_pid, thread2_pid;
 
+static int counter1 = 0;
+static int counter2 = 0;
+
 static void *thread1(void *args)
 {
     (void)args;
 
     msg_t msg_req, msg_resp;
-    int counter = 0, success = 1;
+    int success = 1;
 
     msg_resp.content.ptr = NULL;
-    msg_req.content.ptr = &counter;
+    msg_req.content.ptr = &counter1;
 
     for (int i = 0; i < TEST_EXECUTION_NUM; i++) {
         msg_send_receive(&msg_req, &msg_resp, thread2_pid);
 
         if ((NULL == msg_resp.content.ptr) ||
-            (&counter != ((int *) msg_req.content.ptr)) ||
-            (counter != (*(int *) msg_resp.content.ptr)) ||
-            (counter != (*(int *) msg_req.content.ptr))) {
+            (&counter1 != ((int *) msg_req.content.ptr)) ||
+            (counter1 != (*(int *) msg_resp.content.ptr)) ||
+            (counter1 != (*(int *) msg_req.content.ptr))) {
             success = 0;
             break;
         }
@@ -74,9 +77,8 @@ static void *thread2(void *args)
     (void)args;
 
     msg_t msg_req, msg_resp;
-    int counter = 0;
 
-    msg_resp.content.ptr = &counter;
+    msg_resp.content.ptr = &counter2;
 
     for (int i = 0; i < TEST_EXECUTION_NUM; i++) {
         msg_receive(&msg_req);