ppp: Patch to stop CU179 Testing error msg - pppd uses obsolete (PF_INET, SOCK_PACKET)

ppp: Patch to stop CU179 Testing error msg - pppd uses obsolete (PF_INET, SOCK_PACKET)

- This issue was found by Peter Müller in the CU179 Testing evaluation.
- The issue was found to have already been raised and closed on the ppp github issues page.
- Patch for fix downloaded and applied to this submission.
- When ppp-2.5.1 is released then this patch can be removed.
- update of rootfile not required.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>