tests: kernel: msgq_api: Migrate to K_THREAD_STACK_DECLARE

This commit updates all deprecated `K_THREAD_STACK_EXTERN` macro usages
to use the `K_THREAD_STACK_DECLARE` macro instead.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

tests/kernel/msgq/msgq_api/src/main.c

@@ -12,6 +12,9 @@
  */
 
 #include <ztest.h>
+
+#include "test_msgq.h"
+
 extern void test_msgq_thread(void);
 extern void test_msgq_thread_overflow(void);
 extern void test_msgq_isr(void);
@@ -57,7 +60,7 @@ extern struct k_msgq kmsgq;
 extern struct k_msgq msgq;
 extern struct k_sem end_sema;
 extern struct k_thread tdata;
-K_THREAD_STACK_EXTERN(tstack);
+K_THREAD_STACK_DECLARE(tstack, STACK_SIZE);
 
 /*test case main entry*/
 void test_main(void)

tests/kernel/msgq/msgq_api/src/test_msgq_purge.c

@@ -6,7 +6,7 @@
 
 #include "test_msgq.h"
 
-K_THREAD_STACK_EXTERN(tstack);
+K_THREAD_STACK_DECLARE(tstack, STACK_SIZE);
 extern struct k_thread tdata;
 extern struct k_msgq msgq;
 static ZTEST_BMEM char __aligned(4) tbuffer[MSG_SIZE * MSGQ_LEN];