Fixes for ticket:10, ticket:18, and ticket:19. Merged r3194:3215 from

Fixes for ticket:10, ticket:18, and ticket:19. Merged r3194:3215 from
/gnuradio/branches/developers/jcorgan/ticket-10.  'make distcheck' now
successfully completes on a machine that has never had gnuradio installed
before.  In addition, several cleanups and refactoring of build system
code have been applied.  NOTE: gr-audio-portaudio, gr-audio-osx, and
gr-audio-windows have not been fully tested and will need verification
by the maintainers of these components.

git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@3216 221aa14e-8319-0410-a670-987f0aec2ac5