libjaylink: Update to latest master branch

The changes since the last update are mainly related to the build
system, preparations and cleanups for the upcoming release.

If there are no bugs reported, this will be the last update before the
libjaylink 0.1.0 release.

Change-Id: I4cec9bb61159f6153690aaf39c1d12ba0baacf9b
Signed-off-by: Marc Schink <openocd-dev@marcschink.de>
Reviewed-on: http://openocd.zylin.com/3886


Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>