obexd: Fix string_read when reading chunks
obexd: Fix string_read when reading chunks

The chunks normally are not NUL terminate which might cause strlen to
cause an invalid read.

The fix is basically use GString len to calculate how much data can be
copy in advance and use memcpy to do the job.

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