[flang][NFC] Small refactor for `IsProcedurePointer`

[unterumarmung]

Summary

Instead of manually checking for procedure-like details in Symbol,
defer it to IsProcedure function.

[klausler]

Is this change motivated by a test case for which the predicate is wrong, or does it just seem like a good idea?

[unterumarmung]

I just thought it was a good idea, I tried it, ran the tests and they passed, so I submitted it to the review. I'm not sure that it is a correct change.
If there were a test case, I would've definitely added it to the test suite.

[klausler]

LGTM; thanks!

[kiranchandramohan]

This is probably not an issue so feel free to ignore it. IsPointer is working on the symbol but IsProcedure internally gets the ultimate symbol, hence there is a difference in what each function is working on and also a difference from the existing implementation.

flang/lib/Evaluate/tools.cpp

 const Symbol *FindCommonBlockContaining(const Symbol &original) {
   const Symbol &root{GetAssociationRoot(original)};
   const auto *details{root.detailsIf<ObjectEntityDetails>()};
   return details ? details->commonBlock() : nullptr;
 }
 
 bool IsProcedurePointer(const Symbol &original) {
   const Symbol &symbol{GetAssociationRoot(original)};
-  return IsPointer(symbol) &&
-      (symbol.has<ProcEntityDetails>() || symbol.has<SubprogramDetails>());
+  return IsPointer(symbol) && IsProcedure(symbol);
 }
 
 // 3.11 automatic data object
 bool IsAutomatic(const Symbol &original) {
   const Symbol &symbol{original.GetUltimate()};
   if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
     if (!object->isDummy() && !IsAllocatable(symbol) && !IsPointer(symbol)) {
       if (const DeclTypeSpec * type{symbol.GetType()}) {