[clang] [AArch64][Clang] Fix linker error for function multiversioning (PR #74358)

[via cfe-commits]

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@@ -1752,8 +1754,10 @@ static void AppendTargetClonesMangling(const CodeGenModule &CGM,
   const TargetInfo &TI = CGM.getTarget();
   if (TI.getTriple().isAArch64()) {
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DanielKristofKiss wrote:

As I see for other targets `"default"` is just copied as a feature string.
For AArch64 we want to have clones per feature or set of features instead of CPU.
```c
__attribute__((target_clones("crc32", "aes+sha1")))
int foo(){..}
```

would give 3 clones; the default, `crc32` and one for `aes` plus `sha1` mangled as `foo.default`, `foo._Mcrc32`,` foo._Msha1Maes` respectively.
Also "aes+sha1" should be the same as "sha1+aes" after mangling.


https://github.com/llvm/llvm-project/pull/74358