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

[James Henderson via llvm-commits]

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@@ -1,8 +1,15 @@
+## Show that a proper error message is printed when decompressing sections
+## using unsupported format (zlib). Since both --decompress-debug-sections
+## and --compress-sections with format set to 'none' performs decompression,
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jh7370 wrote:

performs -> perform

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