cmd/compile: mention issue 28603 when discussing where inline marks go

Update #28603

Change-Id: I8bdbea57b3661e15dcc760d27252b794daa476db
Reviewed-on: https://go-review.googlesource.com/c/go/+/177697Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

src/cmd/compile/internal/gc/inl.go

@@ -1046,10 +1046,11 @@ func mkinlcall(n, fn *Node, maxCost int32) *Node {
 	}
 	newIndex := Ctxt.InlTree.Add(parent, n.Pos, fn.Sym.Linksym())
 
-	// Add a inline mark just before the inlined body.
+	// Add an inline mark just before the inlined body.
 	// This mark is inline in the code so that it's a reasonable spot
 	// to put a breakpoint. Not sure if that's really necessary or not
 	// (in which case it could go at the end of the function instead).
+	// Note issue 28603.
 	inlMark := nod(OINLMARK, nil, nil)
 	inlMark.Pos = n.Pos.WithIsStmt()
 	inlMark.Xoffset = int64(newIndex)