staging: lustre: ptlrpc: avoid warning on missing return

The newly added function triggers a harmless warning:

drivers/staging/lustre/lustre/ptlrpc/pack_generic.c: In function 'lustre_shrink_msg':
drivers/staging/lustre/lustre/ptlrpc/pack_generic.c:472:1: error: control reaches end of non-void function [-Werror=return-type]

This probably happens because LASSERTF() contains an 'unlikely()' that sometimes prevents gcc from analysing the control flow correctly. Adding a return statement here seems harmless and lets us keep that unlikely().

---
 drivers/staging/lustre/lustre/ptlrpc/pack_generic.c | 1 +
 1 file changed, 1 insertion(+)

index 13f00b7cbbe5..b1170277fd84 100644
@@ -469,6 +469,7 @@ int lustre_shrink_msg(struct lustre_msg *msg, int segment,
 	default:
 		LASSERTF(0, "incorrect message magic: %08x\n", msg->lm_magic);
 	}
+	return 0;
 }
 EXPORT_SYMBOL(lustre_shrink_msg);
 

2.9.0