similar to: [LLVMdev] MCJIT and DWARF debugging info and lldb

MCJIT attempts to register DWARF debugging information with ELF objects, but I don't believe it does so with MachO. This is a historical artifact due to the fact that those of us who worked on the ELF part of this didn't know how to do the same thing with MachO. Notably, to get it to work correctly RuntimeDyldELF updates some headers to point to the live code before it is registered. We