how to i get both clang and gcc4.2.1 in buildworld ?

As the subject says...
i upgraded to stable/10 without special options, clang is the
default compiler but the gcc4.2.1 whose sources are in the tree
is not compiled.

Is there any way to get both gcc and clang compiled during a buildworld ?
Or any port that brings in the gcc 4.2.1 (and not one of the more
modern ones ?)

For those curious, the reason i am asking is the following,
and it might well be unrelated to gcc:

i used to build picobsd with gcc, and part of picobsd's boostrap
is a "make toolchain". When i hosted this on stable/9 with gcc
i could cross build picobsd using basically any source tree.

Now, however, hosting the build on stable/10 with clang,
the "make toolchain" on a stable/9 tree fails and i need to
do a full "make buildworld" to bootstrap.

I don't know what fails exactly, but i see a ton of warnings
and possibly errors in the 'make toolchain' phase that i
thought might be due to a compiler/source mismatch.
Maybe not. In any case, I'd still like to have gcc.

cheers
luigi