buildroot

spice: add upstream security fixes for CVE-2017-7506

Fixes CVE-2017-7506 - Possible buffer overflow via invalid monitor
configurations.

For more details, see:
https://marc.info/?l=oss-security&m=150001782924095

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>