[clang] Allow the no_stack_protector attribute on local variables (PR #173311)

[Aaron Ballman via cfe-commits]

================
@@ -312,6 +312,10 @@ def warn_stack_clash_protection_inline_asm : Warning<
   "unable to protect inline asm that clobbers stack pointer against stack "
   "clash">, InGroup<DiagGroup<"stack-protector">>;
 
+def warn_stack_protection_ignore_attribute : Warning<
+  "'stack_protector_ignore' attribute ignored due to "
+  "'-fstack-protector-all' option">;
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AaronBallman wrote:

This needs to be in a warning group. I think the ignored attributes warning group makes the most sense.
```suggestion
  "'-fstack-protector-all' option">, InGroup<IgnoredAttributes>;
```

https://github.com/llvm/llvm-project/pull/173311