De-duplicate getGlobalSymbol code

Add a helper function that performs the last step for both cases.  In
particular, this means that we now check if the symbol is in the
global case.

M2/Macaulay2/d/actors5.d

@@ -1581,23 +1581,24 @@ fillnodes(n:LexNode):void := (
 fillnodes(baseLexNode);
 setupconst("operatorNames",Expr(operatorNames));
 
+createSymbol(w:Word, d:Dictionary, s:string):Expr := (
+    if !isvalidsymbol(s) then buildErrorPacket("invalid symbol")
+    else if d.Protected then (
+	buildErrorPacket("attempted to create symbol in protected dictionary"))
+    else (
+	t := makeSymbol(w, tempPosition, d);
+	globalFrame.values.(t.frameindex)));
+
 getglobalsym(d:Dictionary,s:string):Expr := (
      w := makeUniqueWord(s,parseWORD);
      when lookup(w,d.symboltable) is x:Symbol do Expr(SymbolClosure(globalFrame,x))
-     is null do (
-          if !isvalidsymbol(s) then return buildErrorPacket("invalid symbol");
-	  if d.Protected then return buildErrorPacket("attempted to create symbol in protected dictionary");
-	  t := makeSymbol(w,tempPosition,d);
-	  globalFrame.values.(t.frameindex)));
+     is null do createSymbol(w, d, s));
 
 getglobalsym(s:string):Expr := (
      w := makeUniqueWord(s,parseWORD);
      when globalLookup(w)
      is x:Symbol do Expr(SymbolClosure(if x.thread then threadFrame else globalFrame,x))
-     is null do (
-	  if globalDictionary.Protected then return buildErrorPacket("attempted to create symbol in protected dictionary");
-	  t := makeSymbol(w,tempPosition,globalDictionary);
-	  globalFrame.values.(t.frameindex)));
+     is null do createSymbol(w, globalDictionary, s));
 
 getGlobalSymbol(e:Expr):Expr := (
      when e