scripts: runner: use ss on linux, not netstat

Netstat is deprecated.

Reported-by: Leandro Pereira <leandro.pereira@intel.com>
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
diff --git a/scripts/support/runner/core.py b/scripts/support/runner/core.py
index ddf4d60..04fedf4 100644
--- a/scripts/support/runner/core.py
+++ b/scripts/support/runner/core.py
@@ -117,12 +117,12 @@
         return self._parser_windows(cmd)
 
     def _used_now_linux(self):
-        cmd = ['netstat', '-a', '-n', '-t']
-        return self._parser_linux_darwin(cmd)
+        cmd = ['ss', '-a', '-n', '-t']
+        return self._parser_linux(cmd)
 
     def _used_now_darwin(self):
         cmd = ['netstat', '-a', '-n', '-p', 'tcp']
-        return self._parser_linux_darwin(cmd)
+        return self._parser_darwin(cmd)
 
     def _parser_windows(self, cmd):
         out = subprocess.check_output(cmd).split(b'\r\n')
@@ -130,7 +130,12 @@
                       if x.startswith(b'  TCP')]
         return {int(b) for b in used_bytes}
 
-    def _parser_linux_darwin(self, cmd):
+    def _parser_linux(self, cmd):
+        out = subprocess.check_output(cmd).splitlines()[1:]
+        used_bytes = [s.split()[3].rsplit(b':', 1)[1] for s in out]
+        return {int(b) for b in used_bytes}
+
+    def _parser_darwin(self, cmd):
         out = subprocess.check_output(cmd).split(b'\n')
         used_bytes = [x.split()[3].rsplit(b':', 1)[1] for x in out
                       if x.startswith(b'tcp')]