Provide cross compiling SDK
Multiarch applications like Steam or Winepak need to be able to compile 32 bits dependencies. But in general we should allow cross-compiling. For example Gnome Builder should be able to use flatpak to compile towards embedded.
Since we use multiarch we can easily provide cross-compiling abilities.
.Sdk.Compat.*extensions. We have only
.Platform.Compat.*. But we need library symbolic links and maybe some static libraries to support fully.
Make a sdk extension for gcc towards others architectures. We might want to enable this only for
x86_64to avoid having 27 different cross compilers.
Downstream issues depending on it: