tinyCrypt: Initial commit towards ECDHE support

This commit is a first step towards using uECC for ECDH
during TLS handshakes.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 2a50db6..a1c26d0 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -12165,6 +12165,13 @@
     }
 }
 
+#if defined(MBEDTLS_USE_TINYCRYPT)
+int mbetls_uecc_rng_wrapper( uint8_t *dest, unsigned int size )
+{
+    return( mbedtls_ssl_conf_rng_func( NULL, dest, size ) );
+}
+#endif /* MBEDTLS_USE_TINYCRYPT */
+
 #if defined(MBEDTLS_ECP_C)
 /*
  * Check if a curve proposed by the peer is in our list.