devel/jrtplib : upgrade to 3.11.2

The original author step off the project, so for now, update the
WWW link to point to the archived page who describes the project.

Major changes:

• Taking EINTR in nanosleep, poll and select calls into account. Thanks to Filippo Guerzoni (filippo.guerzoni@gmail.com) for bringing this to my attention.
• Disabled some copy constructors
• Bugfix in RTPExternalTransmitter: a buffer could fill up causing the an operation to fail to get aborted
• Added constructor to RTPRawPacket to guess RTP/RTCP type
• Bugfixed regarding some calles being cut short due to an EINTR