srcdir builds

[Arnaud Charlet]

> Phil, I think that the clearest reading of the SC's comments would
> suggest that you also remove your patch from the branch.  Some people
> indicated that since we did not know for sure that things were broken,
> we should assume that they were not.  (I am more paranoid; since I do
> not know that things are working, I wanted to be defensive.)

FYI, things are broken on the branch. One example is that doing a
simple make for c+ada languages now does a bootstrap. Of course I won't
speak about all the assumptions that this change broke, such as location of
object and automatically generated files, as well as build procedures.

I know that building with srcdir=objdir is no longer officially supported,
but it works just fine for e.g c+ada builds, and since building Ada
involves a "cd gcc && make gnatlib_and_tools", having the creation of
an object dir happening magically breaks assumptions made up to now.

Arno