build: Add fix for GCC null-dereference check

Turn off GCC null-dereference check on specific test code, which
should not be executed anyway.

Signed-off-by: Gabor Toth <gabor.toth@arm.com>
Change-Id: Icf4d90ad92a63ffe170c43e8ff065e7ffb940008

Author: gbrtth

api-tests/ff/ipc/test_i047/test_supp_i047.c

@@ -1,5 +1,5 @@
 /** @file
- * Copyright (c) 2019-2024, Arm Limited or its affiliates. All rights reserved.
+ * Copyright (c) 2019-2025, Arm Limited or its affiliates. All rights reserved.
  * SPDX-License-Identifier : Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -206,9 +206,21 @@ int32_t server_test_psa_get_with_invalid_msg_pointer(void)
         val->print(PRINT_ERROR, "\tFailed to set boot flag after check\n", 0);
     }
 
+    /* GCC null-dereference check fails because of invalid_msg, however this
+     * part should not be reached according the comment above.
+     */
+    #if defined(__GNUC__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wnull-dereference"
+    #endif
+
     /* Reject the connection */
     psa->reply(invalid_msg->handle, PSA_ERROR_CONNECTION_REFUSED);
 
+    #if defined(__GNUC__)
+    #pragma GCC diagnostic pop
+    #endif
+
     return VAL_STATUS_SPM_FAILED;
 }