Inline comments on non-primitive options are not parsed

[bufdev]

Test to reproduce:

// assume Help is a message such as:
//
// message HelpMessage {
//   string string_field = 1;
// }

func TestNonPrimitiveOptionComment(t *testing.T) {
	proto := `
// comment
option Help = { string_field: "value" }; // inline`
	p := newParserOn(proto)
	pr, err := p.Parse()
	if err != nil {
		t.Fatal(err)
	}
	o := pr.Elements[0].(*Option)
	if got, want := o.Comment != nil, true; got != want {
		t.Fatalf("got [%v] want [%v]", got, want)
	}
	if got, want := o.Comment.Lines[0], " comment"; got != want {
		t.Fatalf("got [%v] want [%v]", got, want)
	}
	if got, want := o.InlineComment != nil, true; got != want {
		t.Fatalf("got [%v] want [%v]", got, want)
	}
	if got, want := o.InlineComment.Lines[0], " inline"; got != want {
		t.Fatalf("got [%v] want [%v]", got, want)
	}
}