[clang] [clang-tools-extra] [NFC] Add explicit #include llvm-config.h where its macros are used, clang part. (PR #107301)

[Daniil Fukalov via cfe-commits]

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@@ -15,6 +15,7 @@
 #include "clang/Driver/InputInfo.h"
 #include "clang/Driver/Options.h"
 #include "clang/Driver/SanitizerArgs.h"
+#include "llvm/Config/llvm-config.h" // for LLVM_HOST_TRIPLE
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dfukalov wrote:

Well, I guess such files (with configuration defines only) make almost no impact in compile time. It seems reasonable to treat _them_ (only?) just as IWYU.

Moreover, this change is a preparation to cleanup. So this include will probably appear here, after removal in other (implicitly used from this file) place.

https://github.com/llvm/llvm-project/pull/107301