CMake: switch examples/conformance to our git repo
CMake: switch examples/conformance to our git repo

... until our patches are merged upstream. Also
switches the CTS to build using CMake, and
speeds up test_half in short suite.

pocl/pocl,franz/pocl,franz/pocl,Oblomov/pocl,Oblomov/pocl,Oblomov/pocl,pocl/pocl,Oblomov/pocl,franz/pocl,Oblomov/pocl,pocl/pocl,pocl/pocl,franz/pocl,pocl/pocl,franz/pocl