[clang] Extend -Wnonportable-include-path with a warning about trailing whitespace or dots (PR #96960)

[via cfe-commits]

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@@ -1543,3 +1543,6 @@ def ExtractAPIMisuse : DiagGroup<"extractapi-misuse">;
 // Warnings about using the non-standard extension having an explicit specialization
 // with a storage class specifier.
 def ExplicitSpecializationStorageClass : DiagGroup<"explicit-specialization-storage-class">;
+
+// Warnings about non-portable include paths
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zmodem wrote:

nit: period at the end

https://github.com/llvm/llvm-project/pull/96960