Update p5-Plack from version 0.9938 to version 0.9940.

Upstream changes:
0.9940  Fri Jul  2 23:37:51 PDT 2010
        - Fixed META.yml

0.9939  Fri Jul  2 17:56:10 PDT 2010
        - Improved middleware documentation (miyagawa, leedo, bobtfish)
        - Added a test about Transfer-Encoding with Content-Length: 0 (chiba)
        - Fixed NullLogger middleware (haarg)
        - Fixed Plack::Util inline object's can() (haarg)
        - Middleware::HTTPException now honors ->location method of the exception (frodwith)
        - Middleware::AccessLog: Fixes %D to be microsec so it's compatible to Apache #119 (cho45)
        - Fixed Plack::Request->uri when PATH_INFO conatins URI reserved characters #118 (leedo)

(seb)