Fix path output for GoErrCheck
Fix path output for GoErrCheck

With recent changes to the way errcheck is called (using ExecuteInDir),
prepending the GOPATH results in invalid expansion.

t-yuki/vim-go,ebfe/vim-go,andviro/vim-go,vim-IDE/vim-go,andviro/vim-go,vim-IDE/vim-go,vim-IDE/vim-go,wheelcomplex/vim-go