[CMake] Path to installed target

[Alexey Livshits]

> Yes, make the tests run without installation. To give more advice, we'd
> need to know more about those "dependencies". Are they other
> executables? Data files? Libraries?

Well, if I could do that, I wouldn't ask ;)
I have 2 versions, which are built from the same sources. So I have to
have 2 different output directories. Some shared libraries are built
only for one version, but needed for both. CMake install process helps
perfectly here.
Some tests require shared libraries from both versions. So I created
the new install component for tests, but I cannot address them for
CTest.
-- 
BG,
Alexey