[CMake] Multiple library configurations with the same output name

[Alexey Livshits]

> I am not a Visual Studio user so I may be missing your point here
> but why having foo_1 and foo_2 ending up in the same workspace is a problem?
>
> As long as the lib/dll end up in separate dirs (using *_OUTPUT_DIRECTORY).

Workspaces become too large, so I would like make'em smaller.

> Should work too.

Any other possibility?

Thank you.
-- 
BG,
Alexey