Import mbedtls-2.16.0

Imports mbedTLS 2.16.0 from https://github.com/ARMmbed/mbedtls.git
commit fb1972db23da ("Merge pull request #544 from ARMmbed/version-2.16")
(tag mbedtls-2.16.0).

Certain files will never be needed and are thus removed (reducing number
of lines to almost 50%):
rm -f circle.yml CMakeLists.txt DartConfiguration.tcl Makefile
rm -f .gitignore .travis.yml .pylint
rm -f include/.gitignore include/CMakeLists.txt library/.gitignore
rm -f library/CMakeLists.txt library/Makefile
rm -rf .git .github doxygen configs programs scripts tests visualc yotta

This is a complete overwrite of previous code so earlier changes in the
branch import/mbedtls-2.6.1 will be added on top of this commit to bring
the changes forward.

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/des.c b/lib/libmbedtls/mbedtls/library/des.c
index 569e56f..ca9e071 100644
--- a/lib/libmbedtls/mbedtls/library/des.c
+++ b/lib/libmbedtls/mbedtls/library/des.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  FIPS-46-3 compliant Triple-DES implementation
  *
  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
@@ -34,6 +34,7 @@
 #if defined(MBEDTLS_DES_C)
 
 #include "mbedtls/des.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -48,11 +49,6 @@
 
 #if !defined(MBEDTLS_DES_ALT)
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
-}
-
 /*
  * 32-bit integer manipulation macros (big endian)
  */
@@ -316,7 +312,7 @@
     if( ctx == NULL )
         return;
 
-    mbedtls_zeroize( ctx, sizeof( mbedtls_des_context ) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_des_context ) );
 }
 
 void mbedtls_des3_init( mbedtls_des3_context *ctx )
@@ -329,7 +325,7 @@
     if( ctx == NULL )
         return;
 
-    mbedtls_zeroize( ctx, sizeof( mbedtls_des3_context ) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_des3_context ) );
 }
 
 static const unsigned char odd_parity_table[128] = { 1,  2,  4,  7,  8,
@@ -553,7 +549,7 @@
     uint32_t sk[96];
 
     des3_set2key( ctx->sk, sk, key );
-    mbedtls_zeroize( sk,  sizeof( sk ) );
+    mbedtls_platform_zeroize( sk,  sizeof( sk ) );
 
     return( 0 );
 }
@@ -567,7 +563,7 @@
     uint32_t sk[96];
 
     des3_set2key( sk, ctx->sk, key );
-    mbedtls_zeroize( sk,  sizeof( sk ) );
+    mbedtls_platform_zeroize( sk,  sizeof( sk ) );
 
     return( 0 );
 }
@@ -604,7 +600,7 @@
     uint32_t sk[96];
 
     des3_set3key( ctx->sk, sk, key );
-    mbedtls_zeroize( sk,  sizeof( sk ) );
+    mbedtls_platform_zeroize( sk,  sizeof( sk ) );
 
     return( 0 );
 }
@@ -618,7 +614,7 @@
     uint32_t sk[96];
 
     des3_set3key( sk, ctx->sk, key );
-    mbedtls_zeroize( sk,  sizeof( sk ) );
+    mbedtls_platform_zeroize( sk,  sizeof( sk ) );
 
     return( 0 );
 }