vmstate-static-checker: Fix for current python

Python 3.7.5 on f31 doesn't seem to like the old type=file syntax
on argparse.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20191121185303.51685-1-dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

scripts/vmstate-static-checker.py

@@ -375,9 +375,11 @@ def main():
     help_text = "Parse JSON-formatted vmstate dumps from QEMU in files SRC and DEST.  Checks whether migration from SRC to DEST QEMU versions would break based on the VMSTATE information contained within the JSON outputs.  The JSON output is created from a QEMU invocation with the -dump-vmstate parameter and a filename argument to it.  Other parameters to QEMU do not matter, except the -M (machine type) parameter."
 
     parser = argparse.ArgumentParser(description=help_text)
-    parser.add_argument('-s', '--src', type=file, required=True,
+    parser.add_argument('-s', '--src', type=argparse.FileType('r'),
+                        required=True,
                         help='json dump from src qemu')
-    parser.add_argument('-d', '--dest', type=file, required=True,
+    parser.add_argument('-d', '--dest', type=argparse.FileType('r'),
+                        required=True,
                         help='json dump from dest qemu')
     parser.add_argument('--reverse', required=False, default=False,
                         action='store_true',