Linefeed removed after multi line comments in composite literals

[cckim]

Composite literals have blank lines removed, but it seems to treat the trailing */ of a multi-line comment as a blank line.

If we add the following testcase to composite-literals-leading-lines

var _ = map[string]string{
        /*
        */

        "foo": "bar",
}

formatting produces:

var _ = map[string]string{
        /*
        */ "foo": "bar",
}

This seems like an unintended consequence of f2d9f32

Also, this creates a conflict with gofmt v0.1.7 which wants (removed blank space):

var _ = map[string]string{
        /*
        */"foo": "bar",
}

[mvdan]

Thanks - this seems to be one of the cases where we forgot to check if there are any comments in those "empty" lines we're removing. If there are comments, we don't want to remove their newlines.

Leaving as "good first issue" for a couple of days to see if someone wants to pick it up :)