cmake: use generator expression for testing
cmake: use generator expression for testing

Policy CMP0026 deprecates the LOCATION property. Instead, use a
generator expression to get the location of the output of the target.
This feature was added in 2.8.0, so no version bump is required.

bclemetsonblizzard/vogl,ValveSoftware/vogl,bclemetsonblizzard/vogl,kingtaurus/vogl,bclemetsonblizzard/vogl,ValveSoftware/vogl,ValveSoftware/vogl,bclemetsonblizzard/vogl,ValveSoftware/vogl,bclemetsonblizzard/vogl,kingtaurus/vogl,kingtaurus/vogl,kingtaurus/vogl