$OpenBSD$

Use libvterm from ports.

Index: vendor/github.com/ddevault/go-libvterm/vterm.go
--- vendor/github.com/ddevault/go-libvterm/vterm.go.orig
+++ vendor/github.com/ddevault/go-libvterm/vterm.go
@@ -1,7 +1,7 @@
 package vterm
 
 /*
-#cgo CFLAGS: -std=c11 -I"${SRCDIR}/libvterm/include/"
+#cgo pkg-config: vterm
 #include <vterm.h>
 #include <stdio.h>
 
