Backport semantic order fix for delegates

Issue uncovered by recent mangling fixes. Full D2 PR this change
originates from is #1096
but most stuff there is for pure/@safe and thus not applicable to
D2.

src/func.c

@@ -1097,7 +1097,6 @@ void FuncDeclaration::semantic3(Scope *sc)
                 if (!type->nextOf())
                 {
                     ((TypeFunction *)type)->next = Type::tvoid;
-                    type = type->semantic(loc, sc);
                 }
                 f = (TypeFunction *)type;
             }
@@ -1502,6 +1501,11 @@ void FuncDeclaration::semantic3(Scope *sc)
         sc2->pop();
     }
 
+    if (inferRetType)
+    {
+        type = type->semantic(loc, sc);
+    }
+
     if (global.gag && global.errors != nerrors)
         semanticRun = PASSsemanticdone; // Ensure errors get reported again
     else