Debian X Team, Andreas,
I would like to know when it will be possible to compile Mesa stable or git thanks to cross-building on Debian.
Actually, it is not possible because llvm-4.0 packages for two arch (-dev, -common etc...) cannot cohabitate on the same arch. Amd64/i386 on a amd64 system for example.
The only solution is to use chroot for the 32-bits system ... It will be easiest to use the same arch (amd64) to build Mesa i386/amd64 like Arch or Gentoo.