Import mbedtls-2.16.5

Imports Mbed TLS 2.16.5 from https://github.com/ARMmbed/mbedtls.git
commit 0fce215851cc ("Merge pull request #3053 from
yanesca/bump-version-2.16.5") (tag mbedtls-2.16.5).

Certain files will bever be needed and are thus removed:
 rm -f .gitignore .globalrc .pylintrc .travis.yml
 rm -f CMakeLists.txt DartConfiguration.tcl Makefile
 rm -f include/{.gitignore,CMakeLists.txt}
 rm -f library/{.gitignore,CMakeLists.txt,Makefile}
 rm -rf .git .github configs docs doxygen programs scripts tests visualc

This is a complete overwrite of previous code so earlier changes in the
branch import/mbedtls-2.16.0 will be added on top of this commit to bring
the changes forward.

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/asn1write.c b/lib/libmbedtls/mbedtls/library/asn1write.c
index 871477b..c0b4622 100644
--- a/lib/libmbedtls/mbedtls/library/asn1write.c
+++ b/lib/libmbedtls/mbedtls/library/asn1write.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  * ASN.1 buffer writing functionality
  *
  *  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.
@@ -294,22 +294,28 @@
                           const unsigned char *buf, size_t bits )
 {
     int ret;
-    size_t len = 0, size;
+    size_t len = 0;
+    size_t unused_bits, byte_len;
 
-    size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
+    byte_len = ( bits + 7 ) / 8;
+    unused_bits = ( byte_len * 8 ) - bits;
 
-    // Calculate byte length
-    //
-    if( *p < start || (size_t)( *p - start ) < size + 1 )
+    if( *p < start || (size_t)( *p - start ) < byte_len + 1 )
         return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-    len = size + 1;
-    (*p) -= size;
-    memcpy( *p, buf, size );
+    len = byte_len + 1;
 
-    // Write unused bits
-    //
-    *--(*p) = (unsigned char) (size * 8 - bits);
+    /* Write the bitstring. Ensure the unused bits are zeroed */
+    if( byte_len > 0 )
+    {
+        byte_len--;
+        *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 );
+        ( *p ) -= byte_len;
+        memcpy( *p, buf, byte_len );
+    }
+
+    /* Write unused bits */
+    *--( *p ) = (unsigned char)unused_bits;
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );