Fix perforce options access.
Fix perforce options access.

Not all rbt commands add the perforce command-line options, but the p4client
was accessing them as if they did. Trivial fix.

haosdent/rbtools,halvorlu/rbtools,1tush/rbtools,haosdent/rbtools,reviewboard/rbtools,haosdent/rbtools,beol/rbtools,datjwu/rbtools,halvorlu/rbtools,davidt/rbtools,datjwu/rbtools,datjwu/rbtools,beol/rbtools,davidt/rbtools,halvorlu/rbtools,reviewboard/rbtools,davidt/rbtools,reviewboard/rbtools,beol/rbtools