Avoid out of bounds access in read_csv

If one passes an empty list for the names, things should work.

python/cudf/cudf/_lib/csv.pyx

@@ -450,7 +450,7 @@ def read_csv(
                     col_name = df._data.names[index]
                     df._data[col_name] = df._data[col_name].astype(col_dtype)
 
-    if names is not None and isinstance(names[0], (int)):
+    if names is not None and len(names) and isinstance(names[0], (int)):
         df.columns = [int(x) for x in df._data]
 
     # Set index if the index_col parameter is passed