[libc] Remove 'packaged' GPU build support (#100208)
Summary:
Previously, the GPU built the `libc` in a fat binary version that was
used to pass this to the link job in offloading languages like CUDA or
OpenMP. This was mostly required because NVIDIA couldn't consume the
standard static library version. Recent patches have now created the
`clang-nvlink-wrapper` which lets us do that. Now, the C library is just
included implicitly by the toolchain (or passed with -Xoffload-linker
-lc).
This code can be fully removed, which will heavily simplify the build
(and removed some bugs and garbage files I've encoutnered).
