enxio is broken, don't build it for now

setup.py

@@ -53,13 +53,13 @@ extensions = [
               library_dirs=library_dirs,
               runtime_library_dirs=library_dirs,
               language='c++'),
-    Extension('pygmx.enxio',
-              sources=['pygmx/enxio.pyx'],
-              include_dirs=include_dirs,
-              libraries=['gromacs'],
-              library_dirs=library_dirs,
-              runtime_library_dirs=library_dirs,
-              language='c++'),
+#    Extension('pygmx.enxio',
+#              sources=['pygmx/enxio.pyx'],
+#              include_dirs=include_dirs,
+#              libraries=['gromacs'],
+#              library_dirs=library_dirs,
+#              runtime_library_dirs=library_dirs,
+#              language='c++'),
 
 #    Extension('pygmx.tngio',
 #              sources=['pygmx/tngio.pyx'],