Add 3 more missing inline/visibility attributes

[eugenis]

Summary

These are the cases when an out-of-class definition of a method is marked _LIBCPP_INLINE_VISIBILITY, but the in-class declaration is not. This will start failing when (or if) we switch to attribute((internal_linkage)).

[EricWF]

LGTM. For clang this patch should have no functionality change because clang allows attributes to appear only in the declaration. GCC however was previously ignoring the attributes and only now will it mark those functions as hidden. I don't think this will be an issue though. Do you agree?

[eugenis]

Should be fine.

[eugenis]

r255166

include/bitset

 private:
 #ifdef _LIBCPP_HAS_NO_CONSTEXPR
     void __init(unsigned long long __v, false_type) _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
     void __init(unsigned long long __v, true_type) _NOEXCEPT;
 #endif  // _LIBCPP_HAS_NO_CONSTEXPR
     unsigned long to_ulong(false_type) const;

include/memory

             is_convertible<_Yp*, element_type*>::value,
             shared_ptr&
         >::type
+        _LIBCPP_INLINE_VISIBILITY
         operator=(auto_ptr<_Yp> __r);
 #endif
     template <class _Yp, class _Dp>

         _LIBCPP_INLINE_VISIBILITY
         operator=(unique_ptr<_Yp, _Dp>&& __r);
 #else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+        _LIBCPP_INLINE_VISIBILITY
         operator=(unique_ptr<_Yp, _Dp> __r);
 #endif