Fix EncodingWarning in file_util. Ref #232.

Author: jaraco

distutils/file_util.py

@@ -230,9 +230,5 @@ def write_file(filename, contents):
     """Create a file with the specified name and write 'contents' (a
     sequence of strings without line terminators) to it.
     """
-    f = open(filename, "w")
-    try:
-        for line in contents:
-            f.write(line + "\n")
-    finally:
-        f.close()
+    with open(filename, 'w', encoding='utf-8') as f:
+        f.writelines(line + '\n' for line in contents)