(maint) Update debian packaging to build with correct dependencies

We've removed log4cxx and re2 as dependencies for cfacter, replaced with
boost.log and boost.regex. This requires those obsolete pacakges to be
pulled out of the control file, and the correct boost package to be
added.
Can we change this to set a variable called `POSIX_LIBRARIES` now that this is adding more than just a thread library?  We will also need to change the variable name down below in the `target_link_libraries` call.