added license info for gpc with agg21

svn path=/trunk/matplotlib/; revision=412

Author: jdh2358

MANIFEST.in

@@ -13,4 +13,4 @@ recursive-include examples README *.py *.glade
 prune examples/_tmp_*
 recursive-include src  *.cpp *.c *.h
 recursive-include CXX  *.cxx *.hxx *.c
-recursive-include agg2 *.cpp *.c *.h
+recursive-include agg2 *