utils: osinfo: do not use absolute paths

Project should always used build time customization for all paths. This
enables working at devenv mode and at different distributions and
settings.

Related-To: https://bugzilla.redhat.com/show_bug.cgi?id=1043206
Change-Id: I51be14104b73214602c491383fde6b34ef4f094c
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>