macho: track unwind/dwarf cfi records by symbol rather than atom
This solves the nuance case of compiling hand-crafted assembly files
which do not feature `MH_SUBSECTIONS_VIA_SYMBOLS` flag resulting in
input `Atom`s encompassing multiple symbols each with unique unwind
information.
d6e095de2cJakub Konka committed on 8/2/2023, 7:45:33 PMparent4d7dd16