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

[Ruoyu Qiu via llvm-commits]

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@@ -14,3 +14,30 @@ FileHeader:
   Data:            ELFDATA2LSB
   Type:            ET_EXEC
   Machine:         EM_X86_64
+
+# RUN: cp %t a.out
+# RUN: llvm-objdump -d --mcpu=help 2>&1 \
+# RUN:   | FileCheck %s --check-prefix=CHECK-DEFAULT-FILE
+# RUN: rm a.out
+
+# CHECK-DEFAULT-FILE: Available CPUs for this target:
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cabbaken wrote:

I've applied this style in the latest commit.

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