CMake: quiet undefined variable use with MOLTENVK on non-apple systems

extern/vulkan_memory_allocator/CMakeLists.txt

@@ -8,9 +8,14 @@ set(INC
 
 set(INC_SYS
   ${VULKAN_INCLUDE_DIRS}
-  ${MOLTENVK_INCLUDE_DIRS}
 )
 
+if(APPLE)
+  list(APPEND INC_SYS
+    ${MOLTENVK_INCLUDE_DIRS}
+  )
+endif()
+
 set(SRC
   vk_mem_alloc_impl.cc
 

intern/ghost/CMakeLists.txt

@@ -82,6 +82,17 @@ if(WITH_OPENGL_BACKEND)
 endif()
 
 if(WITH_VULKAN_BACKEND)
+
+  if(APPLE)
+    list(APPEND INC_SYS
+      PUBLIC ${MOLTENVK_INCLUDE_DIRS}
+    )
+
+    list(APPEND LIB
+      ${MOLTENVK_LIBRARIES}
+    )
+  endif()
+
   list(APPEND SRC
     intern/GHOST_ContextVK.cc
 
@@ -90,12 +101,10 @@ if(WITH_VULKAN_BACKEND)
 
   list(APPEND INC_SYS
     PUBLIC ${VULKAN_INCLUDE_DIRS}
-    PUBLIC ${MOLTENVK_INCLUDE_DIRS}
   )
 
   list(APPEND LIB
     ${VULKAN_LIBRARIES}
-    ${MOLTENVK_LIBRARIES}
   )
 
   add_definitions(-DWITH_VULKAN_BACKEND)

source/blender/gpu/CMakeLists.txt

@@ -342,12 +342,25 @@ endif()
 
 
 if(WITH_VULKAN_BACKEND)
+
+  if(APPLE)
+    list(APPEND INC_SYS
+      ${MOLTENVK_INCLUDE_DIRS}
+    )
+
+    list(APPEND LIB
+      ${MOLTENVK_LIBRARIES}
+    )
+  endif()
+
   list(APPEND INC
     ../../../extern/vulkan_memory_allocator
   )
   list(APPEND INC_SYS
     ${VULKAN_INCLUDE_DIRS}
-    ${MOLTENVK_INCLUDE_DIRS}
+  )
+
+  list(APPEND INC_SYS
     ${SHADERC_INCLUDE_DIRS}
   )
   list(APPEND SRC
@@ -357,7 +370,6 @@ if(WITH_VULKAN_BACKEND)
   list(APPEND LIB
     ${VULKAN_LIBRARIES}
     ${SHADERC_LIBRARIES}
-    ${MOLTENVK_LIBRARIES}
     extern_vulkan_memory_allocator
   )