Update the way we handle directories supplied by the user:
- the tarball directory is considered as a local copy, and tarballs are copied to a working area,
- the sources and build directories (CT_SRC_DIR and CT_BUILD_DIR) are now computed, and no longer an option,
- the build dir has been renamed from 'build' to 'targets'.
That should ease preparing a tarball of the resulting target.

The files rh62*.patch are from the Red Hat 6.2 file

binutils-2.13.90.0.2-2.src.rpm

I am trusting here that Red Hat's patches are appropriate for all CPU

types.  If I'm wrong, just remove the offending patch...

- Dan Kegel