libc: Consolidate the size_t and NULL definitions

Consolidate the definition of size_t to one header per AArch, and
the definition of NULL to one header

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
Change-Id: Iecfbad2cf360cfb705ce7aaa981700fd16219b82
diff --git a/include/lib/libc/aarch64/stdio_.h b/include/lib/libc/aarch64/stdio_.h
index 09b0172..afaeadc 100644
--- a/include/lib/libc/aarch64/stdio_.h
+++ b/include/lib/libc/aarch64/stdio_.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,11 +7,6 @@
 #ifndef STDIO__H
 #define STDIO__H
 
-#ifndef SIZET_
-typedef unsigned long size_t;
-#define SIZET_
-#endif
-
 #ifndef SSIZET_
 typedef long ssize_t;
 #define SSIZET_
diff --git a/include/lib/libc/aarch64/stdlib_.h b/include/lib/libc/aarch64/stdlib_.h
deleted file mode 100644
index 531308a..0000000
--- a/include/lib/libc/aarch64/stdlib_.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#ifndef STDLIB__H
-#define STDLIB__H
-
-#ifndef SIZET_
-typedef unsigned long size_t;
-#define SIZET_
-#endif
-
-#endif /* STDLIB__H */
diff --git a/include/lib/libc/aarch64/string_.h b/include/lib/libc/aarch64/string_.h
deleted file mode 100644
index 71c51a6..0000000
--- a/include/lib/libc/aarch64/string_.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#ifndef STRING__H
-#define STRING__H
-
-#ifndef SIZET_
-typedef unsigned long size_t;
-#define SIZET_
-#endif
-
-#endif /* STRING__H */
diff --git a/include/lib/libc/aarch64/time_.h b/include/lib/libc/aarch64/time_.h
deleted file mode 100644
index 8b298a3..0000000
--- a/include/lib/libc/aarch64/time_.h
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#ifndef TIME__H
-#define TIME__H
-
-#ifndef SIZET_
-typedef unsigned long size_t;
-#define SIZET_
-#endif
-
-#endif /* TIME__H */