ioctls: videodev2: check if defines are obsolete

In kernel headers 3.11 the VIDIOC_DBG_G_CHIP_IDENT define is
considered obsolete, therefore removed, generating the following
compiling error:

ioctls/videodev2.c:72:15: error: ‘VIDIOC_DBG_G_CHIP_IDENT’ undeclared here (not in a function)
  IOCTL(VIDIOC_DBG_G_CHIP_IDENT),
               ^

Check the definition of it before using it

Signed-off-by: Andi Shyti <andi@etezian.org>
ioctls: btrfs-control: fix header inclusion order

This patch enables newer linux/btrfs.h in Kernel headers 3.11,
where NULL is not recognized as a define. This is done by
including  stdlib.h before linux/btrfs.h. It gets rid of the
following compiling error:

In file included from ioctls/btrfs-control.c:5:0:
/usr/include/linux/btrfs.h: In function ‘btrfs_err_str’:
/usr/include/linux/btrfs.h:486:11: error: ‘NULL’ undeclared (first use in
    return NULL;
           ^

Signed-off-by: Andi Shyti <andi@etezian.org>