fasl-directory parameter) that works as follows:
- if IKARUS_FASL_DIRECTORY is set to "", no fasl files are produced.
- if IKARUS_FASL_DIRECTORY is set to something other than "", the
string is used as a directory in which fasl files are placed.
- if IKARUS_FASL_DIRECTORY is unset, the directory
$HOME/.ikarus/precompiled is used for fasl output.
- library file names are cannonicalized using file-real-path.
- the fasl file (if produced) is the result of
(string-append (fasl-directory) (file-real-path filename) ext)
where ext is either ".ikarus-32bit-fasl" or ".ikarus-64bit-fasl".
- The old behavior (placing the fasl files in the same place as the
library files) can be achieved by setting IKARUS_FASL_DIRECTORY='/'.
