[clang] [CIR][Dialect] Add SourceLangAttr (PR #152511)

[Bruno Cardoso Lopes via cfe-commits]

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@@ -50,6 +50,43 @@ class CIR_UnitAttr<string name, string attrMnemonic, list<Trait> traits = []>
   let isOptional = 1;
 }
 
+//===----------------------------------------------------------------------===//
+// SourceLanguageAttr
+//===----------------------------------------------------------------------===//
+
+def CIR_SourceLanguage : CIR_I32EnumAttr<"SourceLanguage", "source language", [
+  I32EnumAttrCase<"C", 1, "c">,
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bcardosolopes wrote:

Perhaps add a `TODO` for other languages TBD in the future?

https://github.com/llvm/llvm-project/pull/152511