https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108182
--- Comment #12 from Iain Sandoe <iains at gcc dot gnu.org> --- unfortunately, neither this nor the v4.1 (WIP) is still quite right. Using LIBDIR in the computation of the include paths means that the compiler does not work when it is relocated .. the directory prefix needs to be computed at runtime.
