This does other reworking, such as building in a separate directory
like is recommended by the project.
By importing some changes from Arch, I managed to fix building of
libgcc, which further enables building the rest of the toolchain.
However, building libstdc++ is skipped, as that requires newlib
to build, which itself is not available at this point. Newlib on
the other hand requires a built toolchain to compile. We solve
this by building gcc (complete but without libstdc++) first,
followed by building newlib, followed by building just libstdc++
on its own.
541236ac9e