[clang-tools-extra] [clang-tidy] Ignore pure-virtual in portability-template... (PR #150290)

[Baranov Victor via cfe-commits]

================
@@ -171,3 +171,20 @@ struct NoInstantiation<int, U>{
     };
 };
 } // namespace PartialSpecializationNoInstantiation
+
+namespace PR139031 {
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vbvictor wrote:

nit: IMO `PR-XXXX` or `GH-XXX` namespaces just bloat code without any benefits, `git blame` can do the job.
And if LLVM ever moves from GitHub issue, this number will become meaningless.

```suggestion
namespace PureVirtual {
```

https://github.com/llvm/llvm-project/pull/150290