AuthRpc->ibuf must be 1 larger than AuthRpcMax because auth_rpc
(/sys/src/libauth/auth_rpc.c:83) null-terminates the response.

Reference: /n/sources/patch/applied/authrpcovf
Date: Tue Oct 25 15:56:35 CES 2011
Signed-off-by: quanstro@quanstro.net

--- /sys/include/auth.h	Tue Oct 25 15:55:26 2011
+++ /sys/include/auth.h	Tue Oct 25 15:55:25 2011
@@ -35,7 +35,7 @@
 struct AuthRpc
 {
 	int afd;
-	char ibuf[AuthRpcMax];
+	char ibuf[AuthRpcMax+1];
 	char obuf[AuthRpcMax];
 	char *arg;
 	uint narg;