Fix CMake modules not being added correctly
Fix CMake modules not being added correctly

This allows this project to be more easily included as a
sub-project of another project.

Change-Id: I098f26707f17d20353c91a4adb7bfb83d90a99fa

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools