package/mjpg-streamer: needs headers >= 3.16

package/mjpg-streamer: needs headers >= 3.16

Upstream commit

https://github.com/jacksonliam/mjpg-streamer/commit/29fb2b9a65630721c539a216225288fba9497c49#diff-fc82978386df1046ac9aac8cbe0a129eR825

added the usage of V4L2_EVENT_SOURCE_CHANGE which was added to kernel
version 3.16 with commit "[media] v4l: Add source change event":
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/include/uapi/linux/videodev2.h?id=3cbe6e5bcad0b102c06b9c6029fda75630045475

To compare:
- linux 3.15 without the commit:
  https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/include/uapi/linux/videodev2.h?h=linux-3.15.y
- linux 3.16 is the first kernel with the commit:
  https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/log/include/uapi/linux/videodev2.h?h=linux-3.16.y

Fixes
http://autobuild.buildroot.net/results/4f8/4f8dc7520ee692c665167fda69dc3af66263008f/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>