[clang] Add clang atomic control options and attribute (PR #114841)

[Yaxun Liu via cfe-commits]

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@@ -313,6 +313,8 @@ EXTENSION(datasizeof, LangOpts.CPlusPlus)
 
 FEATURE(cxx_abi_relative_vtable, LangOpts.CPlusPlus && LangOpts.RelativeCXXABIVTables)
 
+FEATURE(atomic_attributes, true)
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yxsamliu wrote:

will change

https://github.com/llvm/llvm-project/pull/114841