INSTALL - Added BSD specific install instructions
src/web/download.html - Referenced BSD specific installation instructions in INSTALL
Makefile - Install targets omit sudo when running as root
src/config/unix/impl_specific.fpc - Unix varial specific dependencies for flx (Empty by default)
src/config/unix/bsd_impl_specific.fpc.in - BSD specific dependencies for flx
buildsystem/flx.py - flx_pkgconfig does dnot by default follow Requires: added optional argument to method flx_pckconfig_flags to _run_flx_pkgconfig
                     and downstream methods _build_link and ultimately supplying flx_pkgconfig arg --rec in method build_flx
fbuild/lib/fbuild/config/c/posix.py - appending pthread to external_libs in class pthread_h
fbuildroot.py - Upon detection of bsd platform copt src/config/unix/bsd_impl_specific.fpc.in build/release/config/impl_specific.fpc
src/config/unix/flx.fpc - added Requires: impl_specific