[compiler-rt] [libFuzzer] Fix incorrect coverage number in fork mode (PR #82335)

[Vitaly Buka via llvm-commits]

https://github.com/vitalybuka approved this pull request.

Thanks for the patch!

I assume no volunteers to add, a test, and I am not ready to do that myself.

But the code with the patch is better than without, so no reason to block it.

https://github.com/llvm/llvm-project/pull/82335