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/include/drivers/arm/arm_gic.h b/include/drivers/arm/arm_gic.h
index 019159f..8d2a232 100644
--- a/include/drivers/arm/arm_gic.h
+++ b/include/drivers/arm/arm_gic.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,6 +7,7 @@
 #ifndef __ARM_GIC_H__
 #define __ARM_GIC_H__
 
+#include <cdefs.h>
 #include <stdint.h>
 
 /*******************************************************************************