the Alpha no longer needs -fno-for-scope. However, NetBSD/Alpha's
(cygnus snapshot) g++ doesn't allow virtual functions which aren't
declared inline to be later defined as inline without a warning (-> error).
Therefore, on the Alpha, define BROKEN_GXX_VIRTUAL_INLINE (which will
go away after the Alpha is upgraded to use a more recent toolchain), and
use it to make sure that declarations of virtual functions which will
be defined inline are actually marked as inline when they're declared.