obexd: Ignore NULL sent in x-obex/folder-listing replies
obexd: Ignore NULL sent in x-obex/folder-listing replies

Some broken implementations send send NULL at the ending
of the listing.

silent-snowman/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,mapfau/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,pkarasev3/bluez,mapfau/bluez,mapfau/bluez,ComputeCycles/bluez,pkarasev3/bluez