Fix after review.

Author: Krzysztof Chomski

setup.py

@@ -645,7 +645,7 @@ def pxd(name):
 # ----------------------------------------------------------------------
 # ujson
 
-if suffix == '.pyx' and 'setuptools' in sys.modules:
+if suffix == '.pyx':
     # undo dumb setuptools bug clobbering .pyx sources back to .c
     for ext in extensions:
         if ext.sources[0].endswith(('.c', '.cpp')):