From: Chris Tusa <chris.tusa@leafscale.com>
Subject: st/st.c: openpty() header include for Hammerhead

The bundled st (simple terminal) code's openpty() include is gated on
__linux / BSD-family / __APPLE__ macros only. GCC on Hammerhead
(illumos derivative) predefines none of these, so <libutil.h> (the
header illumos itself ships openpty() in - confirmed present at
/usr/include/libutil.h) never gets included and openpty() is an
implicit (and, under GCC14, error-level) declaration. Add a fallback
#else including the same illumos-native libutil.h.

diff --git a/st/st.c b/st/st.c
--- a/st/st.c	2026-01-17 10:07:39.000000000 -0600
+++ b/st/st.c	2026-07-22 20:52:24.005607327 -0500
@@ -31,6 +31,8 @@
 #include <util.h>
 #elif defined(__FreeBSD__) || defined(__DragonFly__)
 #include <libutil.h>
+#else
+#include <libutil.h>
 #endif
 
 /* Arbitrary sizes */