Import mbedtls-3.6.0

Imports Mbed TLS 3.6.0 from https://github.com/Mbed-TLS/mbedtls.git
tags mbedtls-3.6.0, v3.6.0

Files that are not needed are removed:

cd lib/libmbedtls
rm -rf mbedtls
cp -R path/to/mbedtls-3.6.0/mbedtls .
cd mbedtls
rm CMakeLists.txt DartConfiguration.tcl Makefile
rm .gitignore .travis.yml .pylintrc .globalrc .mypy.ini BRANCHES.md
rm include/.gitignore include/CMakeLists.txt library/.gitignore
rm library/CMakeLists.txt library/Makefile
rm -r cmake
rm -rf .git .github doxygen configs programs scripts tests visualc
rm -rf 3rdparty ChangeLog.d docs pkgconfig .gitmodules .readthedocs.yaml
rm library/mps_*
cd ..
git add mbedtls

This time we leave library/psa_* present to enable TLS 1.3 features.

This is a complete overwrite of previous code so earlier changes in the
previous branch import/mbedtls-3.4.0 will be added on top of this commit.

Signed-off-by: Tom Van Eyck <tom.vaneyck@kuleuven.be>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/dhm.c b/lib/libmbedtls/mbedtls/library/dhm.c
index 94137a2..bcc07f5 100644
--- a/lib/libmbedtls/mbedtls/library/dhm.c
+++ b/lib/libmbedtls/mbedtls/library/dhm.c
@@ -2,19 +2,7 @@
  *  Diffie-Hellman-Merkle key exchange
  *
  *  Copyright The Mbed TLS Contributors
- *  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.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
+ *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
  */
 /*
  *  The following sources were referenced in the design of this implementation
@@ -60,10 +48,10 @@
         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
     }
 
-    n = ((*p)[0] << 8) | (*p)[1];
+    n = MBEDTLS_GET_UINT16_BE(*p, 0);
     (*p) += 2;
 
-    if ((int) (end - *p) < n) {
+    if ((size_t) (end - *p) < (size_t) n) {
         return MBEDTLS_ERR_DHM_BAD_INPUT_DATA;
     }
 
@@ -269,7 +257,7 @@
     DHM_MPI_EXPORT(&ctx->G, n2);
     DHM_MPI_EXPORT(&ctx->GX, n3);
 
-    *olen = p - output;
+    *olen = (size_t) (p - output);
 
 cleanup:
     if (ret != 0 && ret > -128) {
@@ -617,8 +605,7 @@
     if (fread(*buf, 1, *n, f) != *n) {
         fclose(f);
 
-        mbedtls_platform_zeroize(*buf, *n + 1);
-        mbedtls_free(*buf);
+        mbedtls_zeroize_and_free(*buf, *n + 1);
 
         return MBEDTLS_ERR_DHM_FILE_IO_ERROR;
     }
@@ -649,8 +636,7 @@
 
     ret = mbedtls_dhm_parse_dhm(dhm, buf, n);
 
-    mbedtls_platform_zeroize(buf, n);
-    mbedtls_free(buf);
+    mbedtls_zeroize_and_free(buf, n);
 
     return ret;
 }