PR77990 refactor unique_ptr to encapsulate tuple

PR77990 refactor unique_ptr to encapsulate tuple

	PR libstdc++/77990
	* include/bits/unique_ptr.h (__uniq_ptr_impl): New type to
	encapsulate implementation details.
	(unique_ptr::unique_ptr(_Up)): Don't copy deleter object.
	(unique_ptr::get, unique_ptr::get_deleter, unique_ptr::release):
	Call member functions of implementation object.
	(unique_ptr<T[], D>): Likewise.
	* python/libstdcxx/v6/printers.py (UniquePointerPrinter): Adjust for
	new implementation.
	* python/libstdcxx/v6/xmethods.py (UniquePtrGetWorker): Likewise.
	* testsuite/20_util/unique_ptr/assign/48635_neg.cc: Adjust dg-error
	lines.
	* testsuite/20_util/unique_ptr/assign/cv_qual.cc: Likewise.
	* testsuite/20_util/unique_ptr/cons/cv_qual.cc: Likewise.
	* testsuite/20_util/unique_ptr/cons/77990.cc: New test.

From-SVN: r241330