Rename mbedtls_ssl_session minor_ver to tls_version

Store the TLS version instead of minor version number in tls_version.

Note: struct member size changed from unsigned char to uint16_t
Due to standard structure padding, the structure size does not change
unless alignment is 1-byte (instead of 2-byte or more)

Note: existing application use which accesses the struct member
(using MBEDTLS_PRIVATE) is compatible on little-endian platforms,
but not compatible on big-endian platforms.  The enum values for
the lower byte of MBEDTLS_SSL_VERSION_TLS1_2 and of
MBEDTLS_SSL_VERSION_TLS1_3 matches MBEDTLS_SSL_MINOR_VERSION_3 and
MBEDTLS_SSL_MINOR_VERSION_4, respectively.

Note: care has been taken to preserve serialized session format,
which uses only the lower byte of the TLS version.

Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com>
diff --git a/library/ssl_client.c b/library/ssl_client.c
index d3f34df..39b65e8 100644
--- a/library/ssl_client.c
+++ b/library/ssl_client.c
@@ -859,7 +859,7 @@
 
         if( ssl->handshake->resume )
         {
-             ssl->minor_ver = ssl->session_negotiate->minor_ver;
+             ssl->minor_ver = ssl->session_negotiate->tls_version & 0xFF;
              ssl->handshake->min_minor_ver = ssl->minor_ver;
         }
         else