Add openbsd and dragonfly support to shm

tools/utils/shm/specific_openbsd.go

@@ -0,0 +1,21 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package shm
+
+import (
+	"fmt"
+)
+
+var _ = fmt.Print
+
+const SHM_DIR = "/tmp"
+
+func modify_pattern(pattern string) string {
+	// https://github.com/openbsd/src/blob/master/lib/libc/gen/shm_open.c
+	if strings.Contains(pattern, "*") {
+		pattern += ".shm"
+	} else {
+		pattern += "*.shm"
+	}
+	return pattern
+}