This should fix compilation errors when -DGMIO_BUILD_TESTS_FAKE_SUPPORT=ON
on travis CI.
Currently travis cmake version is v2.8.7 and it does not support
the INCLUDE_DIRECTORIES target property.
fake_support allows to test compilation of gmio_support
is successful. It provides fake sources of the required
3rd party libraries (Qt and OpenCascade).
Fake sources allows to quickly check if nothing is broken
in gmio_support after API changes.
It will also be useful for CI.
* All options reside in the top-level CMakeLists.txt file
* No need to find gmio library, just add "gmio" as a target dependency
* In tests, link to gmio library instead of recompiling needed source code
