Fixed bug 3670 - CMake IOS haptic error

CMakeLists.txt

@@ -1311,7 +1311,7 @@ elseif(APPLE)
   if(SDL_HAPTIC)
     set(SDL_HAPTIC_IOKIT 1)
     if (IOS)
-      file(GLOB POWER_SOURCES ${SDL2_SOURCE_DIR}/src/haptic/dummy/*.c)
+      file(GLOB HAPTIC_SOURCES ${SDL2_SOURCE_DIR}/src/haptic/dummy/*.c)
       set(SDL_HAPTIC_DUMMY 1)
     else()
       file(GLOB HAPTIC_SOURCES ${SDL2_SOURCE_DIR}/src/haptic/darwin/*.c)