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

[via cfe-commits]

================
@@ -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`:
----------------
MaggieYingYi wrote:

> Only the driver option is documented in the User Manual.

Sorry, I am not familiar the document rule. However, `-emit-pch` is **NOT** a driver option but it is documented in the User Manual.


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