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

[Evgenii Kudriashov via llvm-commits]

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@@ -0,0 +1,225 @@
+## Bail out if a section consisting of symidx is invalid.
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e-kud wrote:

The section is formed by `.symidx` asm directives.

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