Limitations in ICE data sending

[ming]

There are a couple of issues in the current spec and implementation of pj_ice_strans_sendto():

1. The function will return PJ_SUCCESS even if the lower level send operations return PJ_EPENDING. However, the application doesn't know this so if the application overwrites the send buffer before the send completes, then the data sent will be overwritten.
2. Application cannot know the status of the send operation. There's no callback to tell the application, thus even if the function returns PJ_SUCCESS, the data can actually fail to be sent.

Therefore, this ticket will deprecate this function and replaces it with the new API pj_ice_strans_sendto2(), which can return PJ_EPENDING, and notify the application of the sending status via callback on_data_sent().

[ming]

In 6071:

Fixed #2229: Limitations in ICE data sending

[ming]

In 6073:

Re #2229: Fixed typo of variable type ioq op key.

[ming]

In 6108:

Re #2229: Fixed failed pjnath-test

[ming]

In 6155:

Re #2229: Check to send pending data in the buffer even if the send completes immediately, since buffer may have been filled by then.