obexd: Make obc_transfer_put to accept NULL as filename
obexd: Make obc_transfer_put to accept NULL as filename

In that case contents should be valid so the modules can use
obc_transfer_put to create temporary files.

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