cmd/compile/internal/types: don't return *Sym from Pushdcl (it's never used)

Change-Id: Ib55f7ea3f7dcd9d02f6027121663870a65cb886c
Reviewed-on: https://go-review.googlesource.com/39924Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -909,7 +909,7 @@ func (p *noder) commClauses(clauses []*syntax.CommClause) []*Node {
 
 func (p *noder) labeledStmt(label *syntax.LabeledStmt) *Node {
 	lhs := p.nod(label, OLABEL, p.newname(label.Label), nil)
-	lhs.Sym = types.Dclstack
+	lhs.Sym = types.Dclstack // context, for goto restriction
 
 	var ls *Node
 	if label.Stmt != nil { // TODO(mdempsky): Should always be present.

src/cmd/compile/internal/types/scope.go

@@ -46,10 +46,9 @@ func push(pos src.XPos) *Sym {
 
 // Pushdcl pushes the current declaration for symbol s (if any) so that
 // it can be shadowed by a new declaration within a nested block scope.
-func Pushdcl(s *Sym, pos src.XPos) *Sym {
+func Pushdcl(s *Sym, pos src.XPos) {
 	d := push(pos)
 	dcopy(d, s)
-	return d
 }
 
 // Popdcl pops the innermost block scope and restores all symbol declarations