ASDF users typically symlink .asd files into a central registry
directory. Since Windows does not have symlinks, ASDF on Windows is
currently much less user-friendly than on Unix.
However, Windows has "shortcuts", which are actually just regular files
with an .lnk suffix. Cygwin also creates these files to implement its
symlinks, so that Windows displays them as proper shortcuts.
Attached a patch that hacks ASDF's central registry search function to
look for .asd.lnk files.
With this patch, clbuild works in cygwin.