Update the dummy IrDA backend for Mac OS X.

I forgot to update the dummy IrDA backend with the latest changes. The
error, init and cleanup functions have been removed, and the
irda_socket_open function now takes a context pointer.

src/irda_dummy.c

@@ -23,36 +23,9 @@
 
 #include "irda.h"
 
-int
-irda_errcode (void)
-{
-	return 0;
-}
-
-
-const char *
-irda_errmsg (void)
-{
-	return NULL;
-}
-
 
 int
-irda_init (void)
-{
-	return -1;
-}
-
-
-int
-irda_cleanup (void)
-{
-	return -1;
-}
-
-
-int
-irda_socket_open (irda_t **out)
+irda_socket_open (irda_t **out, dc_context_t *context)
 {
     return -1;
 }