[compiler-rt] [llvm] Reapply "compiler-rt: Introduce runtime functions for emulated PAC." (PR #148094)

[Anatoly Trosinenko via llvm-commits]

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@@ -836,7 +839,7 @@ else ()
     append_list_if(COMPILER_RT_ENABLE_CET -fcf-protection=full BUILTIN_CFLAGS)
   endif()
 
-  append_list_if(COMPILER_RT_HAS_STD_C11_FLAG -std=c11 BUILTIN_CFLAGS)
+  append_list_if(COMPILER_RT_HAS_NOSTDINCXX_FLAG -nostdinc++ BUILTIN_CFLAGS)
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atrosinenko wrote:

[note] If a separate `builtin_check_cxx_compiler_flag` function would be required for any C++ compiler, `BUILTIN_CFLAGS` may have to be updated here as well.

https://github.com/llvm/llvm-project/pull/148094