Define _BSD_SOURCE, to get access to POSIX extensions on OpenBSD 4.1+.
diff --git a/configure b/configure
index 507b720..6212243 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 54283 .
+# From configure.in Revision: 55739 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for python 2.6.
 #
@@ -1838,6 +1838,14 @@
 _ACEOF
 
 
+# OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
+# also defined. This can be overridden by defining _BSD_SOURCE
+
+cat >>confdefs.h <<\_ACEOF
+#define _BSD_SOURCE 1
+_ACEOF
+
+
 # The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
 # u_int on Irix 5.3. Defining _BSD_TYPES brings it back.