[clang] [X86] Emit Warnings for frontend options to enable knl/knm specific ISAs. (PR #75580)

[Phoebe Wang via cfe-commits]

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@@ -18,7 +18,7 @@ This test serves two purposes:
 
 The list of warnings below should NEVER grow.  It should gradually shrink to 0.
 
-CHECK: Warnings without flags (65):
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phoebewang wrote:

Maybe it's not a good example. The test is to prevent adding warnings without -W flags. I think we also need the flag here for user to mask the warning.

https://github.com/llvm/llvm-project/pull/75580