[llvm] [llvm-objcopy] Report unsupported formats before compression (PR #202357)

[James Henderson via llvm-commits]

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@@ -16,3 +23,16 @@ Sections:
     Flags:        [ SHF_COMPRESSED ]
     AddressAlign: 8
     Content:      "010000000000000001000000000000000100000000000000789c63040000020002"
+
+## Original yaml
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jh7370 wrote:

Not quite what I had in mind: I would like the instructions for generating the compressed output spelled out, e.g. the yaml2obj and llvm-objcopy commands (as well as the original input like you've got).

https://github.com/llvm/llvm-project/pull/202357