scons: Don't build egl on Windows.

Useless, as there are no drivers for it.

Reviewed-by: Brian Paul <brianp@vmware.com>

src/SConscript

@@ -30,7 +30,7 @@ SConscript('mesa/SConscript')
 if not env['embedded']:
     if env['platform'] not in ('cygwin', 'darwin', 'freebsd', 'haiku', 'windows'):
         SConscript('glx/SConscript')
-    if env['platform'] not in ['darwin', 'haiku', 'sunos']:
+    if env['platform'] not in ['darwin', 'haiku', 'sunos', 'windows']:
         if env['dri']:
             SConscript('egl/drivers/dri2/SConscript')
         SConscript('egl/main/SConscript')