[clang] [clang] Enable descriptions for --print-supported-extensions (PR #66715)

[Balint Cristian via cfe-commits]

================
@@ -198,13 +199,20 @@ static int PrintSupportedExtensions(std::string TargetStr) {
   std::unique_ptr<llvm::TargetMachine> TheTargetMachine(
       TheTarget->createTargetMachine(TargetStr, "", "", Options, std::nullopt));
   const llvm::Triple &MachineTriple = TheTargetMachine->getTargetTriple();
+  const llvm::MCSubtargetInfo *MCInfo = TheTargetMachine->getMCSubtargetInfo();
+  const llvm::ArrayRef<llvm::SubtargetFeatureKV> Features =
+    MCInfo->getAllProcessorFeatures();
+
+  llvm::StringMap<llvm::StringRef> llvmDescMap;
----------------
cbalint13 wrote:

I'll leve it as sugessted ```DescMap```.

https://github.com/llvm/llvm-project/pull/66715