GHA: Factor out building SSL libs to a reusable workflow

GHA: Factor out building SSL libs to a reusable workflow

We amassed a lot of code duplication there. Make
it easier to track the differences between the libraries.

Change-Id: I3d89016ccae297cfa596897c11a518f1ffbe3dc8
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Yuriy Darnobyt <yura.uddr@gmail.com>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1630
Message-Id: <20260420160732.9492-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg36686.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>