PR libstdc++/58839
	* include/bits/shared_ptr_base.h
	(__shared_ptr<T>::__shared_ptr(unique_ptr<U,D>&&)): Only use addressof
	when unique_ptr<U,D>::pointer is not a built-in pointer type.
	* testsuite/20_util/shared_ptr/cons/58839.cc: New.
	* testsuite/20_util/enable_shared_from_this/members/assign.cc: New.
	* testsuite/20_util/enable_shared_from_this/members/unique_ptr.cc: New.

From-SVN: r204184