fixed godef look up in gopath

[ericaro]

Hi buaazp,

Godef plugin makes an unecessary lookup into $GOPATH for the godef executable. Usually the OS does the lookup, and you just need to have godef reachable from the path.

So with this simplification, now 'godef' only need to be in the PATH, and I can install it for all user etc.

Regards,

[yalay]

I have the same idea as you.