package/x11r7/xserver_xorg-server: add upstream security fixes for CVE-2020-14360...

package/x11r7/xserver_xorg-server: add upstream security fixes for CVE-2020-14360 / 25712

Fixes the following security issues:

* CVE-2020-14360 / ZDI CAN 11572 XkbSetMap Out-Of-Bounds Access

  Insufficient checks on the lengths of the XkbSetMap request can lead to
  out of bounds memory accesses in the X server.

* CVE-2020-25712 / ZDI-CAN-11839 XkbSetDeviceInfo Heap-based Buffer Overflow

  Insufficient checks on input of the XkbSetDeviceInfo request can lead to a
  buffer overflow on the head in the X server.

For more details, see the advisory:
https://www.openwall.com/lists/oss-security/2020/12/01/3

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>