$OpenBSD: patch-ETL__pen_h,v 1.1 2020/01/26 22:38:05 cwen Exp $

Unbreak consumers on !clang archs, from:
https://github.com/synfig/synfig/commit/cb05b072fe6fffb4433140c631f422bdbc036722

Index: ETL/_pen.h
--- ETL/_pen.h.orig
+++ ETL/_pen.h
@@ -136,7 +136,8 @@ class generic_pen (public)
 		typedef int value_type;
 		value_type x,y;
 		difference_type(value_type x, value_type y):x(x),y(y) { }
-		value_type &operator[](int i)const { return i?y:x; }
+		const value_type &operator[](int i) const { return i?y:x; }
+		value_type &operator[](int i) { return i?y:x; }
 	};
 
 protected:
