Guard a macro arg in less(1)

[Michael McConville]

ok?


Index: ch.c
===================================================================
RCS file: /cvs/src/usr.bin/less/ch.c,v
retrieving revision 1.16
diff -u -p -r1.16 ch.c
--- ch.c        27 Dec 2015 17:51:19 -0000      1.16
+++ ch.c        15 Mar 2016 17:18:56 -0000
@@ -103,8 +103,8 @@ struct filestate {
  * Macros to manipulate the list of buffers in thisfile->hashtbl[n].
  */
 #define        FOR_BUFS_IN_CHAIN(h, bn) \
-       for (bn = thisfile->hashtbl[h].hnext;  \
-           bn != END_OF_HCHAIN(h);  bn = bn->hnext)
+       for ((bn) = thisfile->hashtbl[h].hnext;  \
+           (bn) != END_OF_HCHAIN(h);  (bn) = (bn)->hnext)
 
 #define        BUF_HASH_RM(bn) \
        (bn)->hnext->hprev = (bn)->hprev; \