It´s seems that after the revision 29 ( now is r31 ) the google_play_service doesn´t have the "libproject" directory
B4X:
Looks like Google just broke down Google Play Services into multiple libraries. You'll find them in <sdk>/extras/google/m2repository/com/google/android/gms, if you also updated Google Repository through the SDK Manager.
The individual libraries are in aar format, so you'll have to extract the jar yourself, if that's what you're after.