[clang] [Driver] Add -Wa, options --crel and --allow-experimental-crel (PR #97378)

[Peter Smith via cfe-commits]

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@@ -801,6 +801,9 @@ def warn_drv_missing_multilib : Warning<
 def note_drv_available_multilibs : Note<
   "available multilibs are:%0">;
 
+def err_drv_experimental_crel : Error<
+  "-Wa,--allow-experimental-crel must be specified to use -Wa,--crel. CREL is experimental and takes a non-standard section type code">;
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smithp35 wrote:

Nit, I think "uses a non-standard section type code" would read better here.  

https://github.com/llvm/llvm-project/pull/97378