Use cmake build system
I got the current need to have lz4 found via CMake for the next version of alice-vision. The Makefile build system doesn't install the required .cmake files (lz4Config.cmake and lz4Targets.cmake) for that to work. I suggest switching lz4 to its included CMake build system as that will take care of this installation step and it seems cleaner to me anyway.
Edited by Sven-Hendrik Haase