Patch is drawn from [1], made a PR at [2].

Eventually, we might consider doing something for GNU binutils too, in
order that we switch (the normal) ld-wrapper to always use this to
leverage ld to resolve libraries, rather than faking it in bash.

[1]: https://github.com/obsidiansystems/cctools-port/tree/libs-normalize
[2]: tpoechtrager/cctools-port#34

Also fix numberous bugs, such as:

 - Not getting confused on more flags taking file arguments.

 - Ensuring children reexport their children, but the original
   binary/library doesn't.

 - Not spawning children when it turns out we just dynamically link
   under the threshold but our total number of inputs exceeeds it.

 - Children were always named `libunnamed-*`, when that name was
   supposed to be the last resort only.

In addition to the script, we also patch ld-wrapper to respect `.dylib`
and `.so` alike. In a future version of nixpkgs, this can be so enabled
by defaut. Newer nixpkgs will probably do this by default.