[clang] [clang] CWG150: add tests and change to unreleased (PR #93758)

[Vlad Serebrennikov via cfe-commits]

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@@ -753,6 +753,46 @@ namespace cwg148 { // cwg148: yes
 
 // cwg149: na
 
+namespace cwg150 { // cwg150: yes
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Endilll wrote:

```suggestion
namespace cwg150 { // cwg150: 19
```

https://github.com/llvm/llvm-project/pull/93758