Using the host compiler in this case seems to be an artifact from an
older change. On x86_64, this approach ended in unsable hybrid binaries
due to incompatible handling of non-trivial return values, i.e.
structures. See '-freg-struct-return' in GCC manual page:
"[...] If there is no standard convention, GCC defaults to
-fpcc-struct-return, except on targets where GCC is the principal
compiler. In those cases, we can choose the standard, and we chose
the more efficient register return alternative."
In other words: All x86_64 Linux systems break the ABI standard :-(
