Use a local copy of the source when building gcc-target (since

Use a local copy of the source when building gcc-target (since
we hacked up the source used to build the cross compiler).

Fix the crt1.o not found problems.  It turns out gcc was thinking
it was acting as a cross compiler, which is clearly not what we
want here.

With this, everything seems to be working nicely for both C
and C++.