Add build rule for python3 (bug #58689). * src/build-python3.mk: Add build rule for python3 version 3.8.3. * dist-files.mk: Add new file to list. * index.html: Add new package to list. * src/build-setuptools.mk: Update to version 44.1.1 (last version compatible with python2). Use python2. Set installation prefix. * src/build-mako.mk: Use python2. Set installation prefix. * src/build-markupsafe.mk: Use python2. Set installation prefix. * src/mesa.mk: Windows rule depends on scons. Use python2. * src/nsis.mk: Depend on scons. Use python2.

# This file is part of MXE.
# See index.html for further information.

This patch has been taken from:
http://bugs.gentoo.org/show_bug.cgi?id=305101
http://repos.archlinux.org/wsvn/packages/gd/trunk/libpng14.patch

--- a/gd_png.c
+++ b/gd_png.c
@@ -149,7 +149,7 @@
 	return NULL;
   }
 
-	if (!png_check_sig (sig, 8)) { /* bad signature */
+	if (png_sig_cmp (sig, 0, 8)) { /* bad signature */
     	return NULL;		/* bad signature */
 	}