[compiler-rt] [FMV][AArch64] Add initial AT_HWCAP3 / AT_HWCAP4 support (PR #161595)

[via llvm-commits]

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@@ -19,9 +18,14 @@ void CONSTRUCTOR_ATTRIBUTE __init_cpu_features(void) {
   if (res)
     return;
 
+  elf_aux_info(AT_HWCAP3, &hwcap3, sizeof hwcap3);
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enh-google wrote:

(or, if we think it makes the intention more clear, guard the __init_cpu_features_constructor() stuff below by `if (hwcap | hwcap2 | hwcap3 | hwcap4)` rather than have an early exit.)

https://github.com/llvm/llvm-project/pull/161595