(See imgui.cpp line 4871)

target_link_directories is not defined on previous CMake versions (used on
the build machines here). Replaced with link_directories instead.

Unsigned int is not defined under Windows (VS). Replace with uint32_t instead.

* ZLib is not a standard lib under windows and has to be found using find_package(..)
* As glm-static is required by lava-vr, we need to make sure to pass it as a target.

Missing assert.h