buildroot

libv4l: fix EVIOCSCLOCKID related compile failure

Fixes [1]:

  keytable.c: In function 'test_event':
  keytable.c:1351:12: error: 'EVIOCSCLOCKID' undeclared (first use in this function)
    ioctl(fd, EVIOCSCLOCKID, &mode);

[1] http://autobuild.buildroot.net/results/8ba380471423bd2491e40103d7b1a45de1bd12ed

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>