spec: Sort BuildRequires sections

Change-Id: Icee7cd1d1e438929cbffd66e0376d3890501925f
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/33506
Reviewed-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>