daemon: dispatch.c should include stdio.h (and stdarg.h)

dispatch.c requires stdio.h (and stdarg.h), however, currently
dispatch.c implicitly relys on rpc/xdr.h to include stdio.h.
If rpc/xdr.h unxpectedly does not include stdio.h, the compilation
of dispatch.c fails.

This can happen, for example, when portablexdr is installed
under /usr/local; because portablexdr's rpc/xdr.h does not
include stdio.h and gcc looks up it not /usr/include/rpc/xdr.h.

Note that stdarg.h is also included according to man va_start,
although stdio.h seems including it anyway.

daemon/dispatch.c

@@ -23,6 +23,9 @@
 
 #include <config.h>
 
+#include <stdio.h>
+#include <stdarg.h>
+
 #include "dispatch.h"
 #include "remote.h"