patchelf.cc: call zeroOutRpath() before removing

[ghost]

Closes #453

[ghost]

My C++ is rusty so apologies if this is clumsily written.

[ghost]

I need to investigate this: #453 (comment)

[Mic92]

I remember we cannot do this: #453 (comment)

Binutils definitly does this optimization so if any of the nix store paths is used in other parts of the program than it messes up the binary. The only way this could work if all dyn entries would be checked before for potential collisions. If you want to go for this solution please open a new PR.