[libc++] Avoid including shared_ptr.h in basic_ostream.h (#121049)

Author: philnik777

libcxx/include/__fwd/memory.h

@@ -20,6 +20,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 template <class _Tp>
 class _LIBCPP_TEMPLATE_VIS allocator;
 
+template <class _Tp>
+class _LIBCPP_TEMPLATE_VIS shared_ptr;
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___FWD_MEMORY_H

libcxx/include/__ostream/basic_ostream.h

@@ -14,7 +14,7 @@
 #if _LIBCPP_HAS_LOCALIZATION
 
 #  include <__exception/operations.h>
-#  include <__memory/shared_ptr.h>
+#  include <__fwd/memory.h>
 #  include <__memory/unique_ptr.h>
 #  include <__new/exceptions.h>
 #  include <__ostream/put_character_sequence.h>