Hi,
As gcc-5 is now become the default in Ubuntu 15.10 (proposed), I did a test build of gpsd.
On Ubuntu; gcc version 5.2.1 20150808 (Ubuntu 5.2.1-15ubuntu1)
gpsd builds, and scons check runs successfully
On Debian, gcc version 5.1.1 20150711 (Debian 5.1.1-14)
gpsd builds, scons check runs successfully, and (because I have device plugged in), gpsmon and ntp are happy.