--- configure.orig	2017-08-12 12:15:04 UTC
+++ configure
@@ -8053,7 +8053,10 @@ case $host_os in
 	cf_xopen_source="-D_DARWIN_C_SOURCE"
 	cf_XOPEN_SOURCE=
 	;;
-(freebsd*|dragonfly*)
+(freebsd*)
+	cf_XOPEN_SOURCE=
+	;;
+(dragonfly*)
 	# 5.x headers associate
 	#	_XOPEN_SOURCE=600 with _POSIX_C_SOURCE=200112L
 	#	_XOPEN_SOURCE=500 with _POSIX_C_SOURCE=199506L