[El] mapserver should not depend on agg, any more

[Mathieu Baudier]

> The dependency on the agg package in https://projects.argeo.org/elgis/svn/factory/trunk/rpmbuild/elgis/mapserver/SPECS/mapserver.spec should not be needed, any more.

Should I also remove the --with-agg compilation flag?

%configure \
...
   --with-agg \
...