Wrong test in function prvTCPSendLoop()

[htibosch]

Description

Thanks to a forum user zugo83 in a post in the FreeRTOS Forum, we saw that the function FreeRTOS_send() would last longer than necessary.

The proposed change is as follows:

     xBytesLeft -= xByteCount;
     xBytesSent += xByteCount;

-    if( ( xBytesLeft == 0 ) && ( pvBuffer == NULL ) )
+    if( ( xBytesLeft == 0 ) || ( pvBuffer == NULL ) )
     {
         /* pvBuffer can be NULL in case TCP zero-copy transmissions are used. */
         break;
     }

This must have been a type that happened when we merged the trees IPv4 with IPv6/multi.

Test Steps

Try send loads of data before and after this change.

Checklist:

• [x] I have tested my changes. No regression in existing tests.
• [x] I have modified and/or added unit-tests to cover the code changes in this Pull Request.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[htibosch]

PS. I found the guilty PR: #317, mea culpa.

[amazonKamath]

Would be good to run iperf before merge