ENH: make sure tests for cpack are run correctly

Tests/X11/CMakeLists.txt

@@ -30,7 +30,7 @@ IF(X11_FOUND)
     install(TARGETS HelloWorldX11 DESTINATION bin)
 
     set(CPACK_BINARY_OSXX11 ON CACHE "" FORCE)
-    set(CPACK_BINARY_PACKAGEMAKER OFF CACHE FORCE )
+    set(CPACK_BINARY_PACKAGEMAKER OFF "" CACHE FORCE )
     set(CPACK_PACKAGE_NAME HelloWorldX11Package)
     set(CPACK_PACKAGE_EXECUTABLES HelloWorldX11 HelloWorldX11)
   ENDIF(APPLE)