switch hostfs_iattr to explicit unsigned short

It's shared between kernel-compiled hostfs_kern and userland-compiled
hostfs_user (it's uml stuff).  Use explicit type instead of playing
silly buggers with mode_t.  It's not a userland API per se; it interacts
between code compiled with types same as for host kernel and, directly
linked to it, code talking to libc.  Both sides come from the same
kernel source...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/hostfs/hostfs.h

@@ -39,7 +39,7 @@
 
 struct hostfs_iattr {
 	unsigned int	ia_valid;
-	mode_t		ia_mode;
+	unsigned short	ia_mode;
 	uid_t		ia_uid;
 	gid_t		ia_gid;
 	loff_t		ia_size;