[llvm] [PowerPC] Support local-dynamic TLS relocation on AIX (PR #66316)

[Amy Kwan via llvm-commits]

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@@ -1622,6 +1629,10 @@ def TLSGDAIX8 :
                      "#TLSGDAIX8",
                      [(set i64:$rD,
                        (PPCTlsgdAIX i64:$offset, i64:$handle))]>;
+// This pseudo is expanded to one copy to put the module handle in R3, then call
+// GETtlsMOD64AIX, and then add variable offset to the output from the call.
+def TLSLDAIX8 : PPCEmitTimePseudo<(outs g8rc:$rD), (ins g8rc:$handle),
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amy-kwan wrote:

```suggestion
// This pseudo is expanded to one copy to put the module handle in R3, the call
// to GETtlsMOD64AIX, and then adds the variable offset to the output from the call.
def TLSLDAIX8 : PPCEmitTimePseudo<(outs g8rc:$rD), (ins g8rc:$handle),
```
Does this make more sense, for here and in `PPCInstrInfo.td`?

https://github.com/llvm/llvm-project/pull/66316