byteify-string: resolve symlink before byteifying

Otherwise the script turns symlinks into regular files.

contrib/byteify-strings.py

@@ -328,6 +328,7 b' def main():'
         'allow-attr-methods': args.allow_attr_methods,
     }
     for fname in args.files:
+        fname = os.path.realpath(fname)
         if args.inplace:
             with editinplace(fname) as fout:
                 with open(fname, 'rb') as fin: