package/screen: bump version to 4.8.0

package/screen: bump version to 4.8.0

Fixes a memory corruption issue in OSC 49 handling.  Notice that this is
only enabled if screen is built with --enable-rxvt_osc, which isn't the case
in Buildroot. From the release notes:

As last fix, fixes potential memory overwrite of quite big size (~768
bytes), and even though I'm not sure about potential exploitability of
that issue, I highly recommend everyone to upgrade as soon as possible.
This issue is present at least since v.4.2.0 (haven't checked earlier).

https://lists.gnu.org/archive/html/screen-devel/2020-02/msg00007.html

Upstream changed the gnu.org URLs to use HTTPS, so adjust
0005-rename-sched_h.patch to match.

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