ctypes: c_ssize_t introduced from 2.7

I do not know it's right or not
callback: fix arg type

cb arg type was mixed up c_void_p and py_object, fix using py_object

Could not get errno EINTR even NLM_F_DUMP_INTR flag set in Python2.6
I can not see where is wrong...
examples: make it working

but ENOBUFS may occur, seems to need buffer tuning
ctypes: c_ssize_t introduced from 2.7

I do not know it's right or not
callback: fix arg type

cb arg type was mixed up c_void_p and py_object, fix using py_object

Could not get errno EINTR even NLM_F_DUMP_INTR flag set in Python2.6
I can not see where is wrong...
examples: make it working

but ENOBUFS may occur, seems to need buffer tuning
test: almost rewrite callback
examples: make it work

but messy too.
Merge branch 'linux-header'

Conflicts:
	examples/graphite/nf-log.py
	tests/cpylmnl/test_callback.py
git: I mistook merge
mmap: add HAS_MNL_MMAP condition