archive.extracted: unbreak on OpenBSD

On OpenBSD, using tar in "legacy" mode, all option flags except for -C and -I
must be contained within the first argument to tar and must not be prefixed by a
hyphen. Since the state automatically adds '-f', we are not running in legacy
mode and as such, all options must be prefixed by a hyphen.

* before
[INFO    ] Executing command ['tar', 'xz', '-f', '/path/to/file.tgz'] in directory '/path/to/extractdir'
[ERROR   ] Command '['tar', 'xz', '-f', '/path/to/file.tgz']' failed with return code: 1
[ERROR   ] stderr: tar: Failed open to read on /dev/rst0: Device not configured
<snip>
Failed:    1

* after
[INFO    ] Executing command ['tar', '-xz', '-f', '/path/to/file.tgz'] in directory '/path/to/extractdir'
<snip>
Succeeded: 1 (changed=1)

salt/states/archive.py

@@ -455,6 +455,9 @@ def extracted(name,
                         append_opt = append_opt.replace('x', '').replace('f', '')
                         tar_shortopts = tar_shortopts + append_opt
 
+            if __grains__['os'] == 'OpenBSD':
+                tar_shortopts = '-' + tar_shortopts
+
             tar_cmd.append(tar_shortopts)
             tar_cmd.extend(tar_longopts)
             tar_cmd.extend(['-f', filename])