A new symbol is added to elf::symtab in 3 steps:
- SymbolTable::insert creates a placeholder.
- Symbol::mergeProperties
- Symbol::replace
Fields referenced by steps 2) and 3) should be initialized in
SymbolTable::insert. traced and referenced were missed previously.
This did not cause problems because compilers generated code that
initialized them (bit fields) to 0.
I am not sure that comments of this patch are valuable. You just initializing fields
because they can be used anywhere in LLD. Not sure it is worth to mention where
they are used/copied.