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

[James Henderson via llvm-commits]

jh7370 wrote:

> When I'm writing the test case accroding to
> 
> > 3. --mcpu=help + --disassemble + no objects specified + other dump options, --triple
> >    a. As 2. but target derived from --triple option value.
> >    b. If a.out doesn't exist, print MCPU help derived from --triple and don't emit an error.
> 
> Is it intended behavior that we don't emit an error if the user specifies -d but a.out doesn't exist?

Yes, that should be an error, I think, same as other dump options.

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