[clang] [clang][CIR] Add missing dependency on MLIR headers (PR #131057)

[via cfe-commits]

darkbuck wrote:

This patch is to fix the build failure once CIR is enabled. The error reads like
```
llvm-project/llvm/../mlir/include/mlir/IR/Location.h:145:10: fatal error: mlir/IR/BuiltinLocationAttributes.h.inc: No such file or directory
```

https://github.com/llvm/llvm-project/pull/131057