Some libstdc++ fixes for -Wdeprecated-copy.

Some libstdc++ fixes for -Wdeprecated-copy.

	* include/bits/stl_deque.h (_Deque_iterator): Constrain constructor
	for conversion to const_iterator.  Add defaulted copy ops.
	* libsupc++/new (bad_alloc): Add defaulted copy ops.
	* libsupc++/exception.h (exception): Add defaulted copy ops.
	* include/std/system_error (system_error): Add defaulted copy ops.
	* include/std/stdexcept (domain_error, invalid_argument)
	(length_error, out_of_range, range_error, overflow_error)
	(underflow_error): Add defaulted copy ops.
	* include/bits/stl_iterator.h (reverse_iterator): Add defaulted
	copy assignment.
	* include/bits/allocator.h (allocator): Add defaulted copy assignment.
	* include/ext/throw_allocator.h (condition_base): Add defaulted
	default and copy ctor and copy assignment.

From-SVN: r260380