Add `tools/osx/builder`, a POSIX sh script to build all dependant
libraries as static, targetted to OS X 10.7, and build the project with
them (also targetted to OS X 10.7.)

ffmpeg currently does not link, as recording functionality is currently
non-functional anyway, this will be fixed later.

MISC:

- set WORKING_DIRECTORY and ERROR_QUIET for all git commands, for the
  cases when the build directory is not under the git checkout

- #include <cerrno> in ConfigManager.cpp as it uses errno

- change `build*` in `.gitignore` to `build/*` so that files starting
  with "build" are not affected