EDIT: Disabling the tests allowed me to successfully compile ITK with VS2017 and VS2013 (I do not have VS2015 to test)
As a final step, I tried to compile ITK with VS2017 (Windows 10): After reducing the path of the build directory to 69 characters to avoid the error mentioned above:
I was able to open Visual Studio, start the build, and I now get 5 failures (still due to the path being too long). So I think for now there is no way to work around the 260 characters limitation.
Disclaimer: I did not try any other path sizes than the ones mentioned in my posts (140 and 69).