Andrew Wiseman <a.wiseman@btclick.com>.
definitions of some of the macros and `the convex' does too.
HAVE_SYS_WAIT_H probably won't be defined on them if they still get
used, but for safety... -- fx */
-#if (defined (HPUX) && !defined (HPUX8)) || defined (convex)
+/* ISC 4.1 doesn't have wait3, but does have sys/wait.h. */
+#if (defined(HPUX) && !defined(HPUX8)) || defined(convex) || defined(ISC4_1)
#undef HAVE_SYS_WAIT_H
#endif