gcc -Wall `pkg-config --cflags glib-2.0, liblocation --libs glib-2.0, liblocation` -o gps gps.cpp

/var/tmp/cc447Dm5.o: In function `main':
gps.cpp:(.text+0x2c): undefined reference to `location_gpsd_control_get_default()'
gps.cpp:(.text+0x38): undefined reference to `location_gps_device_get_type()'
/var/tmp/cc447Dm5.o: In function `start_location(void*)':
gps.cpp:(.text+0x16c): undefined reference to `location_gpsd_control_start(_LocationGPSDControl*)'
/var/tmp/cc447Dm5.o: In function `on_changed(_LocationGPSDevice*, void*)':
gps.cpp:(.text+0x280): undefined reference to `location_gpsd_control_stop(_LocationGPSDControl*)'