[clang] [CIR] Call code gen; create empty cir.func op (PR #113483)

[Erich Keane via cfe-commits]

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@@ -24,9 +27,140 @@ CIRGenModule::CIRGenModule(mlir::MLIRContext &context,
                            clang::ASTContext &astctx,
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erichkeane wrote:

Parm capitalization on this function is odd, usually we use capitals for this in clang?  Was this discussed on the previous patch?

https://github.com/llvm/llvm-project/pull/113483