[clang-tools-extra] [clang-tidy] Header check support for check_clang_tidy.py (PR #175735)

[Baranov Victor via cfe-commits]

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@@ -1,14 +1,7 @@
-// RUN: mkdir -p %t.dir
-// RUN: cp %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h %t.dir/modernize-concat-nested-namespaces.h
-// RUN: %check_clang_tidy -std=c++17 -check-suffix=NORMAL %s modernize-concat-nested-namespaces %t.dir/code -- -header-filter=".*" -- -I %t.dir
-// RUN: FileCheck -input-file=%t.dir/modernize-concat-nested-namespaces.h %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h -check-prefix=CHECK-FIXES
-// Restore header file and re-run with c++20:
-// RUN: cp %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h %t.dir/modernize-concat-nested-namespaces.h
-// RUN: %check_clang_tidy -std=c++20 -check-suffixes=NORMAL,CPP20 %s modernize-concat-nested-namespaces %t.dir/code -- -header-filter=".*" -- -I %t.dir
-// RUN: FileCheck -input-file=%t.dir/modernize-concat-nested-namespaces.h %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h -check-prefix=CHECK-FIXES
+// RUN: %check_clang_tidy -std=c++17 -check-suffix=NORMAL -check-header %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h %s modernize-concat-nested-namespaces %t -- -header-filter=".*" -- -I %S/Inputs/concat-nested-namespaces
----------------
vbvictor wrote:

```suggestion
// RUN: %check_clang_tidy -std=c++17 -check-suffix=NORMAL -check-header %S/Inputs/concat-nested-namespaces/modernize-concat-nested-namespaces.h %s modernize-concat-nested-namespaces %t -- -- -I %S/Inputs/concat-nested-namespaces
```
I think we have `-header-filter=".*"` now by default in clang-tidy, so we can remove it everywhere.

https://github.com/llvm/llvm-project/pull/175735