fix unused warns when no mount backends enabled
fix unused warns when no mount backends enabled


SVN revision: 74575

rvandegrift/e,rvandegrift/e,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,rvandegrift/e,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment