ENH: make sure tests for cpack are run correctly

Tests/X11/CMakeLists.txt

@@ -29,8 +29,8 @@ IF(X11_FOUND)
     TARGET_LINK_LIBRARIES(HelloWorldX11 ${X11_LIBRARIES})
     install(TARGETS HelloWorldX11 DESTINATION bin)
 
-    set(CPACK_BINARY_OSXX11 "ON")
-    set(CPACK_BINARY_PACKAGEMAKER "OFF")
+    set(CPACK_BINARY_OSXX11 ON CACHE "" FORCE)
+    set(CPACK_BINARY_PACKAGEMAKER OFF CACHE FORCE )
     set(CPACK_PACKAGE_NAME HelloWorldX11Package)
     set(CPACK_PACKAGE_EXECUTABLES HelloWorldX11 HelloWorldX11)
   ENDIF(APPLE)