don't search for libjpeg/libpng if tutorials are disabled

Author: wjakob

tutorials/CMakeLists.txt

@@ -5,10 +5,10 @@ include(CMakeDependentOption)
 
 OPTION(EMBREE_TUTORIALS    "Enable to build Embree tutorials" ON)
 
-ADD_SUBDIRECTORY(common/image)
 CMAKE_DEPENDENT_OPTION(EMBREE_TUTORIALS_GLFW  "Enables GLFW usage in tutorials. When disabled tutorial can only render to disk." ON "EMBREE_TUTORIALS" OFF)
 
 IF (EMBREE_TUTORIALS)
+ADD_SUBDIRECTORY(common/image)
 
 IF (EMBREE_TUTORIALS_GLFW)