If this dependency is missing its possible that openssl won't be built
before libgit2 is built and then we won't have git support over SSL
which leaves out a lot of git repos.
This resolves https://github.com/jmesmon/meta-rust/issues/1. This
change is only necessary for systems (like dizzy) that do not
contain poky commit 60d504b431fa7cdc6ded141def7ae18edb1834e5.
Without that commit or this change, do_compile for libgit2 would fail
with the following error:
CMAKE_AR-NOTFOUND cr libgit2.a ...
Error running link command: No such file or directory
Signed-off-by: Paul Osborne <osbpau@gmail.com>