Fix: getNumResult() was wrong in some cases

It was the number of result declarations, which is
different from the number of results when one
result declaration declares more than one
variable, as in `x, y int`.

Author: owen-mc

go/ql/lib/semmle/go/Expr.qll

@@ -1064,7 +1064,7 @@ class FuncTypeExpr extends @functypeexpr, TypeExpr, ScopeNode, FieldParent {
   ResultVariableDecl getAResultDecl() { result = this.getResultDecl(_) }
 
   /** Gets the number of results of this function type. */
-  int getNumResult() { result = count(this.getAResultDecl()) }
+  int getNumResult() { result = count(this.getAResultDecl().getANameExpr()) }
 
   /**
    * Gets the result of this function type, if there is only one.