patch applied (ghc): Tweak darcs-all script

[Claus Reinke]

> There will be one more break when you get that patch, but from then on
> things ought to be OK.

thanks. i did a 'darcs pull -p perl' to get your first patch, then a './darcs-all pull'
to test it with your second, and it seems to work. great, one serious trap closed
at last! i only hope darcs gets fixed this summer.

though converting to perl is rather more work than letting the script copy itself, 
it perhaps less prone to future errors. it does, however, add a pre-configure 
dependency on perl..

btw, did you figure out why the previous version had the issue? as the 
script i sent demonstrated, cygwin shell scripts can even remove themselves 
while running. just the misterious 'darcs-all-0' had that locking problem.

now, if i could finally get that ghc to build and bin-dist all the way through..
has it been a week since my first try?

thanks,
claus