Squashed commit upgrading to mbedtls-2.16.0

Squash merging branch import/mbedtls-2.16.0

9ee2a92de51f ("libmbedtls: compile new files added with 2.16.0")
9b0818d48d29 ("mbedtls: fix memory leak in mpi_miller_rabin()")
2d6644ee0bbe ("libmedtls: mpi_miller_rabin: increase count limit")
d831db4c238a ("libmbedtls: add mbedtls_mpi_init_mempool()")
df0f4886b663 ("libmbedtls: make mbedtls_mpi_mont*() available")
7b0792062b65 ("libmbedtls: refine mbedtls license header")
2616e2d9709f ("mbedtls: configure mbedtls to reach for config")
d686ab1c51b7 ("mbedtls: remove default include/mbedtls/config.h")
50a57cfac892 ("Import mbedtls-2.16.0")

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/xtea.c b/lib/libmbedtls/mbedtls/library/xtea.c
index 41932ca..63821b8 100644
--- a/lib/libmbedtls/mbedtls/library/xtea.c
+++ b/lib/libmbedtls/mbedtls/library/xtea.c
@@ -28,6 +28,7 @@
 #if defined(MBEDTLS_XTEA_C)
 
 #include "mbedtls/xtea.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -42,11 +43,6 @@
 
 #if !defined(MBEDTLS_XTEA_ALT)
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 /*
  * 32-bit integer manipulation macros (big endian)
  */
@@ -80,7 +76,7 @@
     if( ctx == NULL )
         return;
 
-    mbedtls_zeroize( ctx, sizeof( mbedtls_xtea_context ) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_xtea_context ) );
 }
 
 /*