PR libstdc++/80285 optimize std::make_shared for -fno-rtti

PR libstdc++/80285 optimize std::make_shared for -fno-rtti

	PR libstdc++/80285
	* include/bits/shared_ptr_base.h (_Sp_make_shared_tag::_S_ti): Define
	function to get unique fake std::type_info reference.
	(_Sp_counted_ptr_inplace::_M_get_deleter) [!__cpp_rtti]: Compare to
	_S_ti() fake reference.
	(__shared_ptr(_Sp_make_shared_tag, const Alloc&, Args&&...)): Share
	single implementation with or without RTTI enable.
	[!__cpp_rtti]: Pass fake reference to _M_get_deleter.
	* testsuite/20_util/shared_ptr/creation/alloc.cc: Change expected
	allocation and deallocation counts.
	* testsuite/20_util/shared_ptr/creation/single_allocation.cc: New.
	* testsuite/20_util/shared_ptr/creation/single_allocation_no_rtti.cc:
	New.

From-SVN: r247905