Bug#812550: snap-aligner: FTBFS on kfreebsd-amd64: Don't know how to get time in nanos

[Aaron M. Ucko]

Source: snap-aligner
Version: 0.18~1.0~beta.18+dfsg1-2
Severity: important
Justification: fails to build from source

Hello again.

The kfreebsd-amd64 build of snap-aligner failed:

  SNAPLib/Compat.cpp:1029:6: error: #error "Don't know how to get time in nanos 
on your platform"
     #error "Don't know how to get time in nanos on your platform"

I'd suggest broadening #if defined(__linux__) to

    #if defined(_POSIX_TIMERS)  &&  _POSIX_TIMERS > 0

per clock_getres(2).

Thanks!