The inaccurate #111945 condition fixes a PROVIDE regression (#111478)
but introduces another regression: in a DSO link, if a symbol referenced
only by bitcode files is defined as PROVIDE_HIDDEN, lld would not set
the visibility correctly, leading to an assertion failure in
DynamicReloc::getSymIndex (https://reviews.llvm.org/D123985).
This is because `(sym->isUsedInRegularObj || sym->exportDynamic)` is
initially false (bitcode undef does not set `isUsedInRegularObj`) then
true (in `addSymbol`, after LTO compilation).
Fix this by making the condition accurate: use a map to track defined
symbols.
Reviewers: smithp35
Reviewed By: smithp35
Pull Request: https://github.com/llvm/llvm-project/pull/112386
a2359a865a