no pthreads on OpenBSD

bin/9l

diff --git a/bin/9l b/bin/9l
index 04ce0b0..45be51a 100755
--- a/bin/9l
+++ b/bin/9l
@@ -169,7 +169,7 @@
 *OpenBSD*)
 	ld=gcc
 	userpath=true
-	extralibs="$extralibs -lpthread -lutil"
+	extralibs="$extralibs -lutil"
 	;;
 *FreeBSD*)
 	ld=gcc