[clang] Add ability for clang-format-diff to exit with non-0 status (PR #70883)

[Owen Pan via cfe-commits]

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@@ -325,6 +325,7 @@ output of a unified diff and reformats all contained lines with
                           The name of the predefined style used as a fallback in case clang-format is invoked with-style=file, but can not
                           find the .clang-formatfile to use.
     -binary BINARY        location of binary to use for clang-format
+    -non-zero-exit-code   exit with a non-zero status if formatting changes are necessary
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owenca wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/70883