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

[via cfe-commits]

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@@ -1458,6 +1458,20 @@ will be processed from the PCH file. Otherwise, Clang will report an error.
   ``test.h`` since ``test.h`` was included directly in the source file and not
   specified on the command line using ``-include-pch``.
 
+Ignoring a PCH File
+^^^^^^^^^^^^^^^^^^^
+
+To ignore a PCH file using Clang, the `-Xclang -ignore-pch` option is passed to
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MaggieYingYi wrote:

`-emit-pch` is CC1Option option and is documented in the User Manual. Therefore, I added `-ignore-pch` option in the User manual as well.

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