fix ann chan::iob from seg, failed on discontinuous chunks, now each cont part treated as separate chunk

get_held_out.pl - divide corpus of ccl and rel files into two sets in given proportion

In other words, cut out poliqarp from build if this flag is False.
The flag remains forced to be True by default, though.
This is mostly to be able to cut poliqarp out of pure WIN32 build until
such time it actually builds (it doesn't atm).

Was causing troubles for cmake'ing MSVC projects, but apparently everything works without this line
even for gcc makefile projects.