[clang] [Hexagon] Ignore formatting of generated proto files (PR #184427)

[Sam Elliott via cfe-commits]

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@@ -0,0 +1,3 @@
+# Autogenerated Hexagon intrinsic macros.
+hexagon_protos.h
+hvx_hexagon_protos.h
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lenary wrote:

I think you also need `hexagon_circ_brev_intrinsics.h`

The last hexagon file is `hexagon_types.h`, which I don't think is autogenerated, but I'm not sure.

https://github.com/llvm/llvm-project/pull/184427