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

[Björn Schäpers via cfe-commits]

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@@ -185,6 +191,8 @@ def main():
             diff_string = "".join(diff)
             if len(diff_string) > 0:
                 sys.stdout.write(diff_string)
+                if args.non_zero_exit_code:
+                    sys.exit(1)
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HazardyKnusperkeks wrote:

But it may be a breaking change for others if it suddenly does not return 0.

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