[flang] Fix COMMON block lookup for ACC

Do COMMON block lookups for ACC similarly to how OpenMP does it
(see 5198923).

Author: eugeneepshteyn

flang/lib/Semantics/resolve-directives.cpp

@@ -1649,17 +1649,13 @@ void AccAttributeVisitor::Post(const parser::Name &name) {
 
 Symbol *AccAttributeVisitor::ResolveAccCommonBlockName(
     const parser::Name *name) {
-  if (auto *prev{name
-              ? GetContext().scope.parent().FindCommonBlock(name->source)
-              : nullptr}) {
-    name->symbol = prev;
-    return prev;
+  if (!name) {
+    return nullptr;
   }
-  // Check if the Common Block is declared in the current scope
-  if (auto *commonBlockSymbol{
-          name ? GetContext().scope.FindCommonBlock(name->source) : nullptr}) {
-    name->symbol = commonBlockSymbol;
-    return commonBlockSymbol;
+  if (auto *cb{GetProgramUnitOrBlockConstructContaining(GetContext().scope)
+                   .FindCommonBlock(name->source)}) {
+    name->symbol = cb;
+    return cb;
   }
   return nullptr;
 }