xposed代码编译总是编译不过，请大神指教

Last 10 lines from the log:
   frameworks/base/cmds/xposed/libxposed_art.cpp:56: error: undefined reference to 'art::mirror::ArtMethod::xposed_callback_method'
   frameworks/base/cmds/xposed/libxposed_art.cpp:95: error: undefined reference to 'art::mirror::ArtMethod::EnableXposedHook(art::ScopedObjectAccess&, _jobject*)'
   frameworks/base/cmds/xposed/libxposed_art.cpp:152: error: undefined reference to 'art::mirror::Object::Clone(art::Thread*, art::mirror::Class*)'
   collect2: error: ld returned 1 exit status
   build/core/shared_library_internal.mk:68: recipe for target 'out/target/product/generic_x86/obj/SHARED_LIBRARIES/libxposed_art_intermediates/LINKED/libxposed_art.so' failed
   make: *** [out/target/product/generic_x86/obj/SHARED_LIBRARIES/libxposed_art_intermediates/LINKED/libxposed_art.so] Error 1
   make: *** Waiting for unfinished jobs....
   
   #### make failed to build some targets (02:06 (mm:ss)) ####