Add openbsd and dragonfly support to shm

tools/utils/shm/specific_dragonfly.go

@@ -0,0 +1,16 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package shm
+
+import (
+	"fmt"
+)
+
+var _ = fmt.Print
+
+// https://www.dragonflybsd.org/cgi/web-man?command=shm_open&section=3
+const SHM_DIR = "/var/run/shm"
+
+func modify_pattern(pattern string) string {
+	return pattern
+}