Ticket #5615: Avoid calling the same function n times when once is enough

Hi,

Instrumenting cppcheck on that ticket's case (truncated after the declaration of res_200 to have runs that finish in an acceptable amount of time) showed that we spent significant time checking whether "portability" is enabled and accessing some ArrayInfo's declararationId. This trivial patch fixes it, and lowers the average wall time (on 10 consecutive runs) from 13.5s to 11s. Please consider merging.

Cheers,
  Simon