gitpkgv.bbclass: Add a symlink from meta-oe

This is for systemd layer to be used with
out depending on meta-oe eventually gitpkgv
or similar solution should come out of OE-Core

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>