Add Make rule for generating tracker-test.vapi.
Add Make rule for generating tracker-test.vapi.

After a maintainer-clean, Make doesn't know how to generate this file otherwise.

renatofilho/folks2,GNOME/folks,renatofilho/folks,renatofilho/folks2,renatofilho/folks2,renatofilho/folks,pwithnall/folks,pwithnall/folks,renatofilho/folks2,renatofilho/folks,pwithnall/folks,GNOME/folks,renatofilho/folks,GNOME/folks