[clang] [clang-repl] Lay the foundation of pretty printing for C. (PR #89811)

[Aaron Ballman via cfe-commits]

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@@ -42,6 +42,9 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/Host.h"
+
+#include <stdarg.h>
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AaronBallman wrote:

`<cstdarg>` instead?

https://github.com/llvm/llvm-project/pull/89811