[clang] [Frontend][PCH]-Add support for ignoring PCH options (-ignore-pch). (PR #142409)

[Matheus Izvekov via cfe-commits]

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@@ -3348,6 +3348,9 @@ defm pch_codegen: OptInCC1FFlag<"pch-codegen", "Generate ", "Do not generate ",
   "code for uses of this PCH that assumes an explicit object file will be built for the PCH">;
 defm pch_debuginfo: OptInCC1FFlag<"pch-debuginfo", "Generate ", "Do not generate ",
   "debug info for types in an object file built from this PCH and do not generate them elsewhere">;
+def ignore_pch : Flag<["-"], "ignore-pch">, Group<f_Group>,
+  Visibility<[ClangOption, CC1Option]>,
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mizvekov wrote:

```suggestion
  Visibility<[ClangOption]>,
```
This doesn't need to be a frontend option.

https://github.com/llvm/llvm-project/pull/142409