Fix a runtime printf format warning.
Fix a runtime printf format warning.

gcampax/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,gcampax/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,gcampax/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,gcampax/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server