devel/p4: Update to 2024.2 release patch 2 (2907753)

Also, found that there is support to use tcp keepalive settings
which perforce wants to set and which are configurable, but the
implementation is Linux specific.

Add code to fix this portability problem.

Problem is being reported upstream.

While we're here, freshen patch-Jamrules.

PR: 293924
Approved by: antonfb@hesiod.org (maintainer)