Add missing comment block for buffer settings.

src/core/ppm_extents_mp_c.c

@@ -101,3 +101,10 @@ PPM_destroy_extents_mp(void)
 
 FCALLSCSUB0(PPM_destroy_extents_mp,PPM_DESTROY_EXTENTS_MP,
             ppm_destroy_extents_mp)
+/*
+ * Local Variables:
+ * license-project-url: "https://www.dkrz.de/redmine/projects/scales-ppm"
+ * license-markup: "doxygen"
+ * license-default: "bsd"
+ * End:
+ */