net/liveMedia: update to 2020.02.11

2020.02.11:

• Added support for receiving SRTP (encrypted) RTSP streams. Currently only a few RTSP servers support SRTP. Our current RTSP client code is known to support two of them: The Axis and Bosch network cameras. These cameras support SRTP only when the RTSP connection to the camera is over a TLS connection (something that our RTSP client code has supported since early December 2019). (If you manufacture a network camera (or other RTSP server) that supports streaming SRTP, but which our RTSP client code does not yet handle, then please let us know, and we might be able to update our code to support it.) Note that this support for SRTP is currently only for RTSP *clients*. Our RTSP server implementation does not currently support streaming (outgoing) SRTP However, the "LIVE555 Proxy Server" can now be used to proxy back-end SRTP streams. (The front-end streams will be regular RTP.) As usual, if you don't have the "openssl" library, you can compile the code by specifying -DNO_OPENSSL=1 on the command line. (If you do this, you won't be able to connect to RTSP servers over TLS, nor access SRTP streams.) (Many thanks to Thales Group for sponsoring this work.)
• Updated the "LIVE555 Proxy Server" so that it can recognize/handle back-end "rtsps://" URLs.
• Removed a cast that had prevented a file from compiling on MSVC. (Thanks to Jonathan Brady for reporting this.)
• Added a new configuration file "config.macosx-no-openssl" for Mac OS X.