[flang] Fix static build of flang

[klausler]

Summary

An older version of a function (Fortran::semantics::FindFunctionResult) was
left in flang/lib/Semantics/tools.cpp, and this breaks the static library
build due to a conflict with the intended final version in another
file and library. Remove the old code.

flang/lib/Semantics/tools.cpp

return std::visit(
           [](const HostAssocDetails &details) {
             return FindSubprogram(details.symbol());
           },
           [](const auto &) -> const Symbol * { return nullptr; },
       },
       symbol.details());
 }
 
-const Symbol *FindFunctionResult(const Symbol &symbol) {
-  if (const Symbol * subp{FindSubprogram(symbol)}) {
-    if (const auto &subpDetails{subp->detailsIf<SubprogramDetails>()}) {
-      if (subpDetails->isFunction()) {
-        return &subpDetails->result();
-      }
-    }
-  }
-  return nullptr;
-}
-
 const Symbol *FindOverriddenBinding(const Symbol &symbol) {
   if (symbol.has<ProcBindingDetails>()) {
     if (const DeclTypeSpec * parentType{FindParentTypeSpec(symbol.owner())}) {
       if (const DerivedTypeSpec * parentDerived{parentType->AsDerived()}) {
         if (const Scope * parentScope{parentDerived->typeSymbol().scope()}) {
           return parentScope->FindComponent(symbol.name());
         }
       }