[tlbuild] [tex-live] laulatex quiting: fix your writable cachepath

[Karl Berry]

    I planned once to build the binary from the TL SVN, but it seems complex 
    to build only the LuaTeX binary and not all (which would take too much 
    time on my old laptop), is there a way to select only one ?

sh ./Build -g --disable-all-pkgs --enable-luatex

(I admit I haven't tried it and I'm not sure all relevant dependencies
will get automatically reenabled, but that's the basic idea.)

The -g just says to build with only debugging, no optimization, which is
clearly what would be wanted here.

Build is just a trivial wrapper for "configure && make", with all
programs and arguments changeable via environment variables.

There have already been lots of changes to the svn trunk since the TL13
release, though the crash still happens on i386-linux with a luatex
built against the current sources.  If you want to build from the TL13
release sources, you can check it from r30858.

karl