cpudist: create sufficiently large hash table to avoid missing tasks
cpudist: create sufficiently large hash table to avoid missing tasks

This change fixes the cpudist tool to avoid issue when too many tasks
are running.

Fixes #2567 -- cpudist stop working when there are too many fork

iovisor/bcc,iovisor/bcc,brendangregg/bcc,tuxology/bcc,iovisor/bcc,tuxology/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc,iovisor/bcc,tuxology/bcc,iovisor/bcc,brendangregg/bcc,tuxology/bcc,brendangregg/bcc