Use patchelf to edit DT_SONAME and DT_NEEDED entries in ELF objects

[aperezdc]

Instead of the hack we have at the moment, we should use patchelf, which actually understand the structure of ELF binaries and edits them in-place.

Here's a script that was tested on the WPE WebKit bootstrap tarballs we get from Cerbero, which I think could be used as-is:

• https://gist.github.com/aperezdc/120b1af919ad65d4a2b7154339a3913c