make sure to output to haxe.exe whatever the ocaml version

Makefile.win

@@ -1,5 +1,7 @@
 include Makefile
 
+OUTPUT=haxe.exe
+
 NATIVE_LIBS = shell32.lib libs/extc/extc_stubs.obj libs/extc/zlib/zlib.lib
 
 FILTER=sed 's/File "\([^"]\+\)", line \([0-9]\+\), \(.*\)/\1(\2): \3/' tmp.cmi