[llvm] [llvm-objcopy][COFF] Update .symidx values after stripping (PR #153322)

[James Henderson via llvm-commits]

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@@ -0,0 +1,225 @@
+## Bail out if a section consisting of symidx is invalid.
+## It includes both: an unexpected format for patching section data and
+## updating the checksum, as well as data validity.
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jh7370 wrote:

I'm not sure what this sentence is trying to say. Is it trying to describe the behaviours that are going to be tested? If so, I'd just leave that to comments for each individual test case. No need to say that bit at the top too.

https://github.com/llvm/llvm-project/pull/153322