[clang] [Clang][TableGen] Use const pointers for various Init objects in Diagnostic Emitter (PR #112318)

[Erich Keane via cfe-commits]

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@@ -83,7 +83,7 @@ getCategoryFromDiagGroup(const Record *Group,
 static std::string getDiagnosticCategory(const Record *R,
                                          DiagGroupParentMap &DiagGroupParents) {
   // If the diagnostic is in a group, and that group has a category, use it.
-  if (DefInit *Group = dyn_cast<DefInit>(R->getValueInit("Group"))) {
+  if (const DefInit *Group = dyn_cast<DefInit>(R->getValueInit("Group"))) {
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erichkeane wrote:

most of these are actually supposed to be `const auto *`

https://github.com/llvm/llvm-project/pull/112318