Fixed configure check for video4linux2 support.
Fixed configure check for video4linux2 support.

svn path=/trunk/libavg/; revision=5992

th3infinity/libavg,libavg/libavg,scotty007/libavg,libavg/libavg,hoodie/libavg,libavg/libavg,yyd01245/libavg,th3infinity/libavg,th3infinity/libavg,scotty007/libavg,hoodie/libavg,th3infinity/libavg,hoodie/libavg,hoodie/libavg,yyd01245/libavg,yyd01245/libavg,yyd01245/libavg,scotty007/libavg,scotty007/libavg,libavg/libavg