Instead of requiring the user to bump the ulimit in their shell before
starting a bcc script, try to setrlimit automatically when a failure
occurs. Since there is no getrusage for memlock limit, unfortunately we
have to brute force setting the limit. For now, just try bpf() once and
then try to set unlimited ulimit, then try bpf() again.

Fixes: #281
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>