switch to CGO-free builds

vendor/modernc.org/libc/libc_openbsd_amd64.go

@@ -0,0 +1,10 @@
+// Copyright 2021 The Libc Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package libc // import "modernc.org/libc"
+
+type (
+	long  = int64
+	ulong = uint64
+)