Also undef SIMPLEQ_FOREACH_SAFE.

Prevents macro redefinition warning on at least NetBSD 6.1.
2019-01-24 09:50:58 +11:00 · 2019-01-24 09:50:58 +11:00 · f236ca2741
--- a/openbsd-compat/sys-queue.h
+++ b/openbsd-compat/sys-queue.h
@ -81,6 +81,7 @@
 #undef SIMPLEQ_EMPTY
 #undef SIMPLEQ_NEXT
 #undef SIMPLEQ_FOREACH
+#undef SIMPLEQ_FOREACH_SAFE
 #undef SIMPLEQ_INIT
 #undef SIMPLEQ_INSERT_HEAD
 #undef SIMPLEQ_INSERT_TAIL