Make chan->flag 32 bits

16 bits isn't enough to support the various open flags we want to store.
Flags like O_REMCLO were silently getting dropped.

Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>

kern/include/ns.h

diff --git a/kern/include/ns.h b/kern/include/ns.h
index 8e94995..516ed8b 100644
--- a/kern/include/ns.h
+++ b/kern/include/ns.h
@@ -404,7 +404,7 @@
 	int type;
 	uint32_t dev;
 	uint16_t mode;				/* read/write */
-	uint16_t flag;
+	int flag;
 	struct qid qid;
 	int fid;					/* for devmnt */
 	uint32_t iounit;			/* chunk size for i/o; 0==default */