Try to get hg to treat importlib.h as binary.

Python/freeze_importlib.py

@@ -24,6 +24,7 @@ def main(input_path, output_path):
     lines.append('};\n')
     with open(output_path, 'w') as output_file:
         output_file.write('\n'.join(lines))
+        output_file.write('\u0000')
 
 
 if __name__ == '__main__':

Python/importlib.h

@@ -3107,3 +3107,4 @@ unsigned char _Py_M__importlib[] = {
     13,12,9,12,15,12,17,15,2,6,2,12,41,18,25,12,
     23,12,15,24,34,12,45,
 };
+