[llvm] [TargetParser] Parse Amazon Linux triple and handle RuntimeLibcalls (PR #136114)

[Benjamin Maxwell via llvm-commits]

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@@ -173,7 +173,7 @@ void RuntimeLibcallsInfo::initLibcalls(const Triple &TT) {
     setLibcallName(RTLIB::EXP10_F64, "__exp10");
   }
 
-  if (TT.isGNUEnvironment() || TT.isOSFuchsia() ||
+  if (TT.isGNUEnvironment() || TT.isOSFuchsia() || TT.isAmazonLinux() ||
----------------
MacDue wrote:

> Ideally you should switch to `aarch64-amazon-linux-gnu`.

I agree, but I don't think that's a change I can make. AFAIK this is just the triple Amazon Linux uses. 

> As an alternative (but it's not a good idea to not switch to `linux-gnu`, set `Environment` to GNU, perhaps in `Triple::Triple`.

```
/// At its core the Triple class is designed to be a wrapper for a triple
/// string; the constructor does not change or normalize the triple string.
```
That would seem to go against the documentation for `Triple`. 

https://github.com/llvm/llvm-project/pull/136114