Convert two macros into functions.

Convert packet_send_debug and packet_disconnect from macros to
functions.  Some older GCCs (2.7.x, 2.95.x) see to have problems with
variadic macros with only one argument so we convert these two into
functions.  ok djm@
diff --git a/opacket.h b/opacket.h
index 16fcb9e..a0a60e5 100644
--- a/opacket.h
+++ b/opacket.h
@@ -102,10 +102,11 @@
 	ssh_packet_get_string_ptr(active_state, (length_ptr))
 #define packet_get_cstring(length_ptr) \
 	ssh_packet_get_cstring(active_state, (length_ptr))
-#define packet_send_debug(fmt, args...) \
-	ssh_packet_send_debug(active_state, (fmt), ##args)
-#define packet_disconnect(fmt, args...) \
-	ssh_packet_disconnect(active_state, (fmt), ##args)
+void	packet_send_debug(const char *, ...)
+	    __attribute__((format(printf, 1, 2)));
+void	packet_disconnect(const char *, ...)
+	    __attribute__((format(printf, 1, 2)))
+	    __attribute__((noreturn));
 #define packet_have_data_to_write() \
 	ssh_packet_have_data_to_write(active_state)
 #define packet_not_very_much_data_to_write() \