[llvm] [llvm-readobj][ELF] Fix broken JSON output with --dynamic-table (PR #95976)

[Fred Grim via llvm-commits]

feg208 wrote:

> Can you include a snippet in the commit message that shows how the output is changing? We've done that for patches like this in the past, and it helps make clear what the new behavior is.

Done. I added it here and in the commit message

https://github.com/llvm/llvm-project/pull/95976