cfi doesn't gobble stderr messages
I have been redirected with this issue from pypy bug tracker https://bugs.pypy.org/issue1716
pypy-c jitviewer.py -q -c my_file.py
I got those messages (tcl.h not found, tk.h not found) in ubuntu 13.10 until I had installed tcl-dev, tk-dev.
arigo thinks it's due to running "try: import tkinter; except ImportError:..." will print an error message to stderr because cffi doesn't gobble them