For cross gcc I guess the important question is, do we want
gcc-4*.src.rpm to build all the cross compilers (and, is C enough, or
do we need C++ too?), or do we have one cross-gcc-4*.src.rpm that
semi-loosely tracks gcc-4*.src.rpm and builds all the cross compilers
(BuildRequires all the cross-binutils and all
cross-glibc/kernel-headers), or each cross would have its own
src.rpm? I think the last one would be a maitanance nightmare.
It would be nice to have --with arguments to select individual arches
instead of all the cross compilers, and C++ support, perhaps after C.