Overhaul this script a bit:

Overhaul this script a bit:
- build_x.sh now does all the steps to build an X dist rather than being
  a child script of package_x_dists.sh
- Update the usage information to list the ports you need to install
  before running this script as well as needing to set CVSROOT.
- Make sure CVSROOT is set.  If not, exit with an error.
- We now take two parameters: a work directory and an output directory.
  The work directory is used as scratch space.  All of the bindist will
  end up in the output directory.
- Only apply XF86.patch to the checked out XFree86 port if it exists.
- Use XFree86's build-bindist tool to package up the dists using their
  distfiles rather than using our own packing lists that have to be
  manually updated each time the port changes.

Example usage:
	env CVSROOT=/home/ncvs ./build_x.sh /usr/xtmp /usr/x11dists