Paths in error messages for file modules contain dots now

[brson]

These ./ path elements shouldn't exist.

/home/brian/dev/rust3/src/librustdoc/./astsrv.rs:67:15: 67:35 error: unresolved name: task::spawn_listener
/home/brian/dev/rust3/src/librustdoc/./astsrv.rs:67         ch: do task::spawn_listener |move parse, po| {