RFC: gcc/testsuite/gcc.c-family/

[Aldy Hernandez]

It seems every time we add a new front end extension to C/C++, we have
to write up 2 tests to make sure they get tested in both front ends.
I think we should have a set of tests that get run for both front
ends.  It's silly to keep this much duplicity around.

Are there any objections to adding say, testsuite/gcc.c-family/ for
tests that get run for both front ends?  Any gotchas?

Aldy