buildroot

libzip: bump version to 1.2.0

It's a major release, but the API seems to be mostly
backwards-compatible. The only package depending on this library in
buildroot is libsigrok and it builds fine.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>