exp/cmd/godef: should ignore hidden files

[GoogleCodeExporter]

Would it be possible to ignore hidden files when parsing packages? Emacs 
creates hidden symbolic links with names like `.#foo.go` for modified files. 
This seems to trip up godef, meaning it won't be able to find any declarations 
for expressions.

My guess is that it parses both foo.go and .#foo.go and then fails because of 
duplicate function names, among others.

Original issue reported on code.google.com by dominik.honnef on 28 Feb 2013 at 11:09