[CMake] Multiple toolchains

[Denis Scherbakov]

> There was some talk about this a while ago (and a patch
> supplied here)
> http://www.mail-archive.com/cmake@cmake.org/msg13572.html
> 
> I'm a bit curios what happened after this and if the above
> code is possible to achieve now days?

I am also waiting for multiple toolchain support in one source tree, because
I cross compile to many OSes and I have a whole bunch of them.

I think the problem is almost the same as having 32 and 64-bit architectures
in one source tree.

As far as I know, this feature currently is not implemented.

Denis