lcc: Add a bit of actual functionality
gc: Update toolbox
mkx: Fix incompatibilities introduced by 699a6e14647f38f5c0b0f58b2693b997d548ee83

The new version of toolbox to which gc was upgraded by commit 699a6e14647f38f5c0b0f58b2693b997d548ee83
removed the deprecated direct conversion of C strings to atoms. However, mkx
used this deprecated functionality and compilation failed. mkx now performs an
explicit conversion as suggested by the documentation of toolbox.