imagerylib: avoid the compiler warning (discards 'const' qualifier) by explicit const cast

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@57232 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/imagery/iclass_statistics.c

@@ -111,8 +111,8 @@ void I_iclass_free_statistics(IClass_statistics * statistics)
 
     G_debug(4, "free_statistics()");
 
-    G_free(statistics->name);
-    G_free(statistics->color);
+    G_free((char *) statistics->name);
+    G_free((char *) statistics->color);
     G_free(statistics->band_min);
     G_free(statistics->band_max);
     G_free(statistics->band_sum);