libc++ debug mode status

Work is beginning on a libc++ debug mode. The purpose of this table is to record which parts of libc++ have debug mode support.

Section | Completed ?
--- | ---
`vector<T>, T != bool` | ✓
`<list>` | ✓
`<unordered_set>` | ✓
`<unordered_map>` | ✓
`<string>` | ✓
`<set>` |
`<map>` |
`vector<bool>` |
`<deque>` |
`<forward_list>` |
`<array>` |
`<stack>` |
`<queue>` |
`<algorithm>` |

At present the table is known to not be a complete list. It is currently ordered in approximate priority order.