Add DL_EXPORT() to all modules that could possibly be used
on BeOS or Windows.
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 8795463..11b624a 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -339,7 +339,7 @@
 A signal handler function is called with two arguments:\n\
 the first is the signal number, the second is the interrupted stack frame.";
 
-void
+DL_EXPORT(void)
 initsignal()
 {
 	PyObject *m, *d, *x;