More class/struct mixup fixes.

Spotted by Clang.

headers/private/debugger/user_interface/UserInterface.h

@@ -15,7 +15,7 @@
 #include "Types.h"
 
 
-class entry_ref;
+struct entry_ref;
 
 class CpuState;
 class ExpressionInfo;

headers/private/interface/ShapePrivate.h

@@ -27,7 +27,8 @@
 #define OP_SMALL_ARC_TO_CCW	0x08000000
 
 
-struct shape_data : public BReferenceable {
+class shape_data : public BReferenceable {
+public:
 	uint32*	opList;
 	BPoint*	ptList;
 	int32	opCount;

headers/private/shared/HashMap.h

@@ -450,7 +450,7 @@ HashMap<Key, Value>::Size() const
 
 // GetIterator
 template<typename Key, typename Value>
-struct HashMap<Key, Value>::Iterator
+class HashMap<Key, Value>::Iterator
 HashMap<Key, Value>::GetIterator() const
 {
 	return Iterator(this);