append to install target list

Co-authored-by: Charles Giessen <46324611+charles-lunarg@users.noreply.github.com>

Author: M2-TE

Diff for: CMakeLists.txt

@@ -115,12 +115,12 @@ if (VULKAN_HEADERS_ENABLE_INSTALL)
     install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/registry" DESTINATION "${CMAKE_INSTALL_DATADIR}/vulkan" USE_SOURCE_PERMISSIONS)
 
     set_target_properties(Vulkan-Headers PROPERTIES EXPORT_NAME "Headers")
+    list(APPEND INSTALL_TARGETS Vulkan-Headers)
     if (VULKAN_HEADERS_ENABLE_MODULE)
-        set_target_properties(Vulkan-HppModule PROPERTIES EXPORT_NAME "HppModule")
-        install(TARGETS Vulkan-Headers Vulkan-HppModule EXPORT VulkanHeadersConfig INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
-    else()
-        install(TARGETS Vulkan-Headers EXPORT VulkanHeadersConfig INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+            set_target_properties(Vulkan-HppModule PROPERTIES EXPORT_NAME "HppModule")
+            list(APPEND INSTALL_TARGETS Vulkan-HppModule)
     endif()
+    install(TARGETS ${INSTALL_TARGETS} EXPORT VulkanHeadersConfig INCLUDES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 
     install(EXPORT VulkanHeadersConfig NAMESPACE "Vulkan::" DESTINATION "share/cmake/VulkanHeaders")