UFS: disallow truncation to set file size past RLIMIT_FSIZE

This is mandated by POSIX.

PR:	164793
Reviewed by:	asomers, jah, markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D36625

sys/ufs/ufs/ufs_vnops.c

@@ -755,6 +755,9 @@ ufs_setattr(
 			 */
 			return (0);
 		}
+		error = vn_rlimit_trunc(vap->va_size, td);
+		if (error != 0)
+			return (error);
 		if ((error = UFS_TRUNCATE(vp, vap->va_size, IO_NORMAL |
 		    ((vap->va_vaflags & VA_SYNC) != 0 ? IO_SYNC : 0),
 		    cred)) != 0)