buildroot

btrfs-progs: bump to version 4.16

Drop upstream patch.

Add a patch for fixing static build.

Add license information about the newly introduced libbtrfsutil.

Disable the libbtrfsutil python binding. It does not cross compile
nicely.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>