as documented at
https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html

It is now equivalent to do

```
zig objcopy --only-keep-debug bar foo.debug
zig objcopy -g bar foo.tmp
zig objcopy --add-gnu-debuglink=foo.debug foo.tmp foo
rm foo.tmp
```

or

```
zig objcopy --only-keep-debug bar foo foo.debug
zig objcopy -g --add-gnu-debuglink=foo.debug bar foo
```

or

```
zig objcopy -g --extract-to=foo.debug bar foo
```