explorer/disks: Add support for OpenBSD

cdist/conf/explorer/disks

@@ -1,3 +1,16 @@
-#!/bin/sh
+#!/bin/sh -e
+
+os=$("$__explorer/os")
+case "$os" in
+    openbsd)
+        IFS=',' disks=$(sysctl -n hw.disknames)
+        for d in $disks; do
+            echo "${d%%:*}"
+        done | sed -n '/^[sw]d[0-9][0-9]*/p'
+    ;;
+
+    *)
         cd /dev || exit 0
         echo sd? hd? vd?
+    ;;
+esac