Update p5-Plack from version 0.9941 to version 0.9942.

Upstream changes:
0.9942  Fri Jul 23 23:42:43 PDT 2010
        - Allow passing FCGI manager object to Handler::FCGI (confound)
        - Call FCGI::Request::Finish() before pm_post_dispatch (confound)
        - Moved response_cb() to Plack::Util (confound)
        - re-enable WithLexicals now that PadWalker segfaults with 5.12 is fixed #98

(seb)