[llvm] [llvm-objdump] Add triple support to `mcpu=help` (PR #165661)

[Ruoyu Qiu via llvm-commits]

================
@@ -3533,6 +3533,35 @@ commaSeparatedValues(const llvm::opt::InputArgList &InputArgs, int ID) {
   return Values;
 }
 
+static void mcpuHelp() {
+  std::string Error;
+  Triple DummyTriple;
+
+  if (!TripleName.empty())
+    DummyTriple.setTriple(TripleName);
+  else {
+    // If the target triple is derived from the files, we display help message
----------------
cabbaken wrote:

It will detect the file's Triple, so the result is the help message for the ARM architecture. Should we maintain consistency with the original behavior?

https://github.com/llvm/llvm-project/pull/165661