[flang] Cope with homonymous generic/specific in generic resolution

[klausler]

Summary

When a generic interface X has a specific procedure Y that is also a specific
procedure of another generic with the same name (Y), ensure that
generic resolution of a call to X that resolves to Y points to the
symbol of the specific procedure Y, not the generic.

[vdonaldson]

Looks good; thanks.

flang/lib/Semantics/expression.cpp

if (ultimate.attrs().test(semantics::Attr::INTRINSIC)) {
     if (context_.intrinsics().Probe(
             CallCharacteristics{ultimate.name().ToString(), isSubroutine},
             localActuals, foldingContext_) &&
         !buffer.AnyFatalError()) {
       return {&ultimate, false};
     }
   }
   if (const auto *details{ultimate.detailsIf<semantics::GenericDetails>()}) {
-    for (const Symbol &specific : details->specificProcs()) {
+    for (const Symbol &specific0 : details->specificProcs()) {
+      const Symbol &specific{BypassGeneric(specific0)};
       if (isSubroutine != !IsFunction(specific)) {
         continue;
       }
       if (!ResolveForward(specific)) {
         continue;
       }
       if (std::optional<characteristics::Procedure> procedure{
               characteristics::Procedure::Characterize(