Comment 0 for bug 750585

In order to have coinstallable multiarch -dev packages of any sort, linux-libc-dev first needs to be coinstallable since libc-dev depends on it. This seems to be straightforward to achieve; only the asm directory needs to be moved to the multiarch directory path, all the other header files appear to be (sensibly) architecture-neutral and can be shared between architectures.

The compiler will find /usr/include/<triplet>/asm for the corresponding architecture with no problems; I've done a number of test builds that work just fine this way. The only trouble is with software that walks the filesystem looking for asm/<foo>.h includes instead of trusting the compiler to resolve them. It's unlikely that software should need to do this since the asm headers should as a rule not be directly included from userspace anyway, but the chances are not zero. I didn't expect nearly as many packages to break as did by the move to /usr/lib/<triplet>, either, so it seems my faith in the sanity of upstream build systems is generally misplaced. And I don't think we have time to discover any resulting issues with another archive test rebuild and fix the resulting packages before the natty release.