Bah, fix a sign-extension issue.

You would think after 30 years I would have mastered this...

os/frisbee.redux/client.c

@@ -1693,7 +1693,8 @@ PlayFrisbee(void)
 				p->msg.join2.chunksize = MAXCHUNKSIZE;
 				p->msg.join2.blocksize = MAXBLOCKSIZE;
 				p->msg.join2.bytecount =
-					p->msg.join.blockcount * MAXBLOCKSIZE;
+					(uint64_t)p->msg.join.blockcount *
+					MAXBLOCKSIZE;
 			}
 			CLEVENT(1, EV_CLIJOINREP,
 				CHUNKSIZE, BLOCKSIZE,

os/frisbee.redux/decls.h

@@ -290,7 +290,7 @@ typedef struct {
 			int32_t		blockcount;
 			int32_t		chunksize;
 			int32_t		blocksize;
-			int64_t		bytecount;
+			uint64_t		bytecount;
 		} join2;
 
 		/*