package/linphone: port some stuff from mediastreamer

package/linphone: port some stuff from mediastreamer

We need to add some dependencies formerly provided by the mediastreamer
package, also add --disable-video to make clear that our linphone
package lacks video support as stated in Config.in.

Fixes
http://autobuild.buildroot.net/results/45e/45e605de0488e9e961a536f4d232235c5282522b/
http://autobuild.buildroot.net/results/ed5/ed508ac3509be8c46670198da8eb0a2ba74835e6/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>