[ELF] Respect ltoCanOmit for symbols in non-prevailing COMDAT A linkonce_odr definition can be omitted in LTO compilation if `canBeOmittedFromSymbolTable()` is true in all bitcode files. Currently, we don't respect the `canBeOmittedFromSymbolTable()` bit from symbols in a non-prevailing COMDAT, which could lead to incorrect omission of a definition when merging a prevailing linkonce_odr and a non-prevailing weak_odr, e.g. an implicit template instantiation and an explicit template instantiation. To fix #111341, allow the non-prevailing COMDAT code path to clear the `ltoCanOmit` bit, so that `VisibleToRegularObj` could be false in LTO.cpp. We could resolve either an Undefined or a Defined. For simplicity, just use a Defined like the prevailing case (similar to how we resolve symbols in ObjectFile COMDAT reviews.llvm.org/D120626). Pull Request: https://github.com/llvm/llvm-project/pull/119332
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