error code fixes:

* fix TLS layer to consistently use WOLFSSL_FATAL_ERROR for error retvals, rather than literal -1.
* add WC_NO_ERR_TRACE() wrapper around LENGTH_ONLY_E (it does not signify an error condition).
* refactor errcode handling for traceability in wolfSSL_DSA_do_sign(), wolfSSL_DH_size(), wolfSSL_EC_KEY_get_conv_form(), wolfSSL_d2i_DSA_SIG(), wolfSSL_DSA_do_sign(), SetDhInternal(), and wolfSSL_EC_KEY_get_conv_form().

wolfcrypt/src/coding.c

@@ -458,7 +458,7 @@ static int DoBase64_Encode(const byte* in, word32 inLen, byte* out,
     *outLen = i;
 
     if (ret == 0)
-        return getSzOnly ? LENGTH_ONLY_E : 0;
+        return getSzOnly ? WC_NO_ERR_TRACE(LENGTH_ONLY_E) : 0;
 
     return ret;
 }