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

[James Henderson via llvm-commits]

================
@@ -1,12 +1,38 @@
 # RUN: yaml2obj %s -o %t
-# RUN: llvm-objdump -d %t --mattr=help 2>&1 | FileCheck %s
-# RUN: llvm-objdump -d %t --mcpu=help 2>&1 | FileCheck %s
+# RUN: llvm-objdump -d %t --mattr=help 2>&1 \
+# RUN:   | FileCheck %s --check-prefixes=CHECK,CHECK-DISASSEMBLE
+# RUN: llvm-objdump -d %t --mcpu=help 2>&1 \
+# RUN:   | FileCheck %s --check-prefixes=CHECK,CHECK-DISASSEMBLE
+
+## We should be able to retrieve help message without -d.
----------------
jh7370 wrote:

```suggestion
## The help message can be printed without -d.
```
I'd consider moving these cases to the first set, before the pre-existing test case, and then make the "with -d" case a special case showing that printing mcpu=help doesn't interfere with regular disassembly.

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