[llvm] [PowerPC][clang] Fix triple constructor ambiguity causing "unknown" target triple on AIX (PR #147488)

[Matt Arsenault via llvm-commits]

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@@ -55,7 +55,7 @@ static std::string updateTripleOSVersion(std::string TargetTripleString) {
   // On AIX, the AIX version and release should be that of the current host
   // unless if the version has already been specified.
   if (Triple(LLVM_HOST_TRIPLE).getOS() == Triple::AIX) {
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arsenm wrote:

This function shouldn't depend on the host triple in the first place 

https://github.com/llvm/llvm-project/pull/147488