this is going to break n9/n950 support, which don't have CLOCK_BOOTTIME. you need to:
a) check if CLOCK_BOOTTIME is defined (to see if your kernel headers are new enough, always will be on Mer at least)
b) check if clock_gettime(CLOCK_BOOTTIME works
c) fall back to CLOCK_MONOTONIC if it doesn't at runtime (your kernel headers a new, but the actual kernel is old - i.e. n9/n950)

also, please use qFatal("Can't clock_gettime!") if CLOCK_MONOTONIC fails