Volk fixes and a little bit of trouble

After a few fixes, volk + gnuradio seems to be building and qa tests
passing with MSVC: http://gnuradio.org/cgit/jblum.git/log/?h=volk_fixes

The only error seems to be this one:

It looks curiously a bit like this error (which is no longer an issue it
seems): http://gnuradio.org/redmine/issues/468#note-2