libc: Fix all includes in codebase

The codebase was using non-standard headers. It is needed to replace
them by the correct ones so that we can use the new libc headers.

Change-Id: I530f71d9510cb036e69fe79823c8230afe890b9d
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/lib/libc/assert.c b/lib/libc/assert.c
index 721b6e5..2d2396c 100644
--- a/lib/libc/assert.c
+++ b/lib/libc/assert.c
@@ -1,10 +1,11 @@
 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #include <assert.h>
+#include <cdefs.h>
 #include <console.h>
 #include <debug.h>
 #include <platform.h>