Compiler error not linkified if message contains a ":"

[snej]

The following Go compiler error doesn't get turned into a source code link:

rest.go:255: syntax error: unexpected name, expecting semicolon or newline or }

The problem is that Go::link_errs sees that there are three : characters on the line and tries to interpret what's between the second and third :s as a column number, which doesn't work.

link_errs should probably not be counting colons like this. Instead it should use a single regex that optionally recognizes a column number if it's present.