ENH: Allow CMake to use CommandLineArguments without warning

Source/kwsys/CMakeLists.txt

@@ -257,9 +257,11 @@ ENDFOREACH(c)
 
 IF(KWSYS_USE_CommandLineArguments)
   IF(NOT ParaView_SOURCE_DIR)
-    IF(NOT KWSYS_STANDALONE)
-      MESSAGE("Command Line Arguments is experimental code for now")
-    ENDIF(NOT KWSYS_STANDALONE)
+    IF(NOT CMake_SOURCE_DIR)
+      IF(NOT KWSYS_STANDALONE)
+        MESSAGE("Command Line Arguments is experimental code for now")
+      ENDIF(NOT KWSYS_STANDALONE)
+    ENDIF(NOT CMake_SOURCE_DIR)
   ENDIF(NOT ParaView_SOURCE_DIR)
 ENDIF(KWSYS_USE_CommandLineArguments)