[llvm] [llvm-objdump] Support --mcpu=help/--mattr=help without -d (PR #165661)

[James Henderson via llvm-commits]

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@@ -0,0 +1,25 @@
+# RUN: yaml2obj %s -o %t
+# REQUIRES: mips-registered-target,x86-registered-target
+
+## We shoule be able to retrieve help message by triple.
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jh7370 wrote:

```suggestion
## When specifying --triple, the help message should be printed for the specified target.
```

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