Don't copy LLVM shared object on Linux

We copy the LLVM shared object when building Odin on Linux. Contrary the comment in `build_odin.sh`,
this is unnecessary, and Odin can be compiled and itself compile things just fine without this step.

This is then packaged up at release and leads to #4019 and #4033. The Linux release builds are built
on Ubuntu and not strictly supported on other Linux distributions. Building from source is preferred.