[DebugInfo] Fix emission of empty debug_names for Apple

D118754 added a new DICompileUnit::DebugNameTableKind for "Apple", so that,
under DWARF 5, the following combination is used inside DwarfDebug.cpp:

```
(lldb) p getAccelTableKind()
(llvm::AccelTableKind) $6 = Dwarf
(lldb) p CU.getNameTableKind()
(llvm::DICompileUnit::DebugNameTableKind) $7 = Apple
```

This creates a problem in the if statements changed, whereby "for non Apple
AccelTableKind" we emit empty tables for any DebugNameTableKind that is not
"Default". We should consider the newly added kind here too.

Note that our existing test could have caught this, if only it had checked the
_contents_ of the table, instead of merely checking for the existence of the
section.

Differential Revision: https://reviews.llvm.org/D153275