os: Depend on _libc.

os/metadata.txt

@@ -1,4 +1,5 @@
 srctype = micropython-lib
 type = package
-version = 0.1.1
+version = 0.1.2
 author = Paul Sokolovsky
+depends = libc

os/os/__init__.py

@@ -3,13 +3,14 @@ import array
 import struct
 import errno
 import stat as stat_
+import _libc
 try:
     from _os import *
 except:
     pass
 
 
-libc = ffi.open("libc.so.6")
+libc = _libc.get()
 
 errno_ = libc.var("i", "errno")
 mkdir_ = libc.func("i", "mkdir", "si")

os/setup.py

@@ -6,7 +6,7 @@ from setuptools import setup
 
 
 setup(name='micropython-os',
-      version='0.1.1',
+      version='0.1.2',
       description='os module for MicroPython',
       long_description="This is a module reimplemented specifically for MicroPython standard library,\nwith efficient and lean design in mind. Note that this module is likely work\nin progress and likely supports just a subset of CPython's corresponding\nmodule. Please help with the development if you are interested in this\nmodule.",
       url='https://github.com/micropython/micropython/issues/405',
@@ -15,4 +15,5 @@ setup(name='micropython-os',
       maintainer='MicroPython Developers',
       maintainer_email='micro-python@googlegroups.com',
       license='MIT',
-      packages=['os'])
+      packages=['os'],
+      install_requires=['micropython-libc'])