[clang] [clang][AIX] Fix -print-runtime-dir fallback on AIX (PR #141439)

[Daniel Chen via cfe-commits]

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@@ -933,11 +933,16 @@ ToolChain::getTargetSubDirPath(StringRef BaseDir) const {
   if (auto Path = getPathForTriple(T))
     return *Path;
 
-  if (T.isOSAIX() && T.getEnvironment() == Triple::UnknownEnvironment) {
-    // Strip unknown environment from the triple.
-    const llvm::Triple AIXTriple(
-        llvm::Triple(T.getArchName(), T.getVendorName(),
-                     llvm::Triple::getOSTypeName(T.getOS())));
+  if (T.isOSAIX()) {
+    llvm::Triple AIXTriple;
+    if (T.getEnvironment() == Triple::UnknownEnvironment) {
+      // Strip unknown environment from the triple.
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DanielCChen wrote:

Nit: this effectively strips the OSVersion as well. Since we moved them together, may be explicitly say it in the comment to make it clear. 

https://github.com/llvm/llvm-project/pull/141439