Bug#1000461: add support for gcc-12

[Helmut Grohne]

Package: cross-gcc-dev
Version: 245
User: helm...@debian.org
Usertags: rebootstrap

Hi Dima,

can you add gcc-12 support? If you're short on time, just copy the
gcc-11 patches to gcc-12. If you have more time, you can try rebasing.

Helmut