Incorrect SSL function prototypes

[John.Ohl]

The function prototypes `SSL_TcpGetLastRxTime` and `SSL_TcpSendKeepAlive` are defined in <crypto/ssl.h>, however the real functions are defined in ssl.cpp as `SSL_GetLastRxTime` and `SSL_SendKeepAlive`.

[dciliske]

Indeed you are correct. I have no idea how/when this happened during the TLS update, but this has been corrected. The implementation now matches the header prototypes.

-Dan