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

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@@ -31,6 +31,16 @@ option:
 
   $ clang -cc1 -include-pch test.h.pch test.c -o test.s
 
+To ignore PCH options using ``clang -cc1``, use the option `-ignore-pch`:
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MaggieYingYi wrote:

> I will update -ignore-pch as a driver option which is similar as the -include-pch option. Once -ignore-pch is a driver option, it needs to be documented on the UserManual.

Updated the patch in the commit https://github.com/MaggieYingYi/llvm-project/commit/9e6e7e741b56d81807cf07f53e8e94e0ce3f56cb.

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