Merge branch 'mbedtls-1.3' into development

* mbedtls-1.3:
  Deprecate HAVE_INT8 and HAVE_INT16
  Deprecate using NET_C without HAVE_IPV6
  Officially deprecate compat-1.2.h and openssl.h
  Document POLARSSL_CAMELLIA_SMALL_MEMORY
  Fix bug with ssl_set_curves() check on client
  Fix bug in POLARSSL_PLATFORM_STD_EXIT support