[llvm] [llvm-readobj,ELF] Support --decompress/-z (PR #82594)

[James Henderson via llvm-commits]

================
@@ -0,0 +1,67 @@
+# REQUIRES: zlib
+## Test --decompress/-z
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jh7370 wrote:

```suggestion
## Test --decompress/-z.
```
Nit.

https://github.com/llvm/llvm-project/pull/82594