STYLE: check autoPtr as plain bool instead of valid()

- cleaner code, more similarity with unique_ptr

  Now
      if (ptr)
      if (!ptr)

  instead
      if (ptr.valid())
      if (!ptr.valid())

applications/utilities/preProcessing/setExprFields/setExprFields.C

@@ -802,9 +802,9 @@ int main(int argc, char *argv[])
                 ctrl
             );
         }
-        else if (exprDictPtr.valid())
+        else if (exprDictPtr)
         {
-            const dictionary& exprDict = exprDictPtr();
+            const dictionary& exprDict = *exprDictPtr;
 
             // Read set construct info from dictionary
             PtrList<entry> actions(exprDict.lookup("expressions"));
@@ -898,7 +898,7 @@ int main(int argc, char *argv[])
                 );
             }
         }
-        else if (exprDictPtr.valid())
+        else
         {
             FatalErrorInFunction
                 << "No command-line or dictionary??" << nl << endl