[flang] Fix intrinsic/generic interaction regression

[klausler]

Summary

When resolving a procedure reference, do not allow a successful
intrinsic procedure probe result to override an existing
symbol.

[klausler]

Merge two patches together (both need to be present to fix problem without adding a test failure)

flang/lib/Semantics/expression.cpp

   }
   if (!resolution) {
     // Not generic, or no resolution; may be intrinsic
-    if (!symbol->attrs().test(semantics::Attr::EXTERNAL)) {
-      if (std::optional<SpecificCall> specificCall{context_.intrinsics().Probe(
-              CallCharacteristics{ultimate.name().ToString(), isSubroutine},
-              arguments, GetFoldingContext())}) {
-        CheckBadExplicitType(*specificCall, *symbol);
-        return CalleeAndArguments{
-            ProcedureDesignator{std::move(specificCall->specificIntrinsic)},
-            std::move(specificCall->arguments)};
-      } else if (symbol->attrs().test(semantics::Attr::INTRINSIC)) {
-        return std::nullopt;
+    bool isIntrinsic{symbol->attrs().test(semantics::Attr::INTRINSIC)};
+    if (!isIntrinsic && !isGenericInterface) {
+      resolution = symbol;
+    } else if (std::optional<SpecificCall> specificCall{
+                   context_.intrinsics().Probe(
+                       CallCharacteristics{
+                           ultimate.name().ToString(), isSubroutine},
+                       arguments, GetFoldingContext())}) {
+      CheckBadExplicitType(*specificCall, *symbol);
+      return CalleeAndArguments{
+          ProcedureDesignator{std::move(specificCall->specificIntrinsic)},
+          std::move(specificCall->arguments)};
+    } else {
+      if (!isIntrinsic) {
+        EmitGenericResolutionError(*symbol, dueToNullActual);
       }
-    }
-    if (isGenericInterface) {
-      EmitGenericResolutionError(*symbol, dueToNullActual);
       return std::nullopt;
-    } else {
-      // Neither a generic interface nor an intrinsic
-      resolution = symbol;
     }
   }
   if (resolution->GetUltimate().has<semantics::DerivedTypeDetails>()) {