Fixed cmake issues

cmake/OpenCVModule.cmake

@@ -663,7 +663,7 @@ macro(_ocv_create_module)
   set(sub_objs "")
   set(sub_links "")
   set(cuda_objs "")
-  if (DEFINED OPENCV_MODULE_${the_module}_CHILDREN)
+  if (OPENCV_MODULE_${the_module}_CHILDREN)
     status("Complex module ${the_module}")
     foreach (m ${OPENCV_MODULE_${the_module}_CHILDREN})
       if (BUILD_${m} AND TARGET ${m}_object) # ambigous?
@@ -765,7 +765,9 @@ macro(_ocv_create_module)
   if (TARGET ${the_module}_object)
     # copy COMPILE_DEFINITIONS
     get_target_property(main_defs ${the_module} COMPILE_DEFINITIONS)
-    set_target_properties(${the_module}_object PROPERTIES COMPILE_DEFINITIONS ${main_defs})
+    if (main_defs)
+      set_target_properties(${the_module}_object PROPERTIES COMPILE_DEFINITIONS ${main_defs})
+    endif()
     # use same PCH
     if (TARGET pch_Generate_${the_module})
       add_dependencies(${the_module}_object pch_Generate_${the_module} )