gfx940 and gfx941 are no longer supported. This is one of a series of
PRs to remove them from the code base.

For SWDEV-512631 and SWDEV-512633

Summary:
A few of these were out of date, update them now that the C library
interface into RPC was deleted.

Summary:
I added a wrapper linker awhile back but this still says it doesn't
work.

This reverts commit 550b83d658755664a7f0f93b36242e885743a91b.

Summary:
I forgot that the OpenMP tests still look for this, reverting for now
until I can make a fix.

This reverts commit c1c6ed83e9ac13c511961e5f5791034a63168e7e.

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).

Summary:
This documentation was lagging reality and didn't contain much. Update
it with some more information now that it's more mature.

Summary:
After the overhaul of the GPU build the documentation pages were a
little stale. This updates them with more in-depth information on
building the GPU runtimes and using them. Specifically using them goes
through the differences between the offloading and direct compilation
modes.

Summary:
There are a lot of random training spaces on various lines. This patch
just got rid of all of them with `sed 's/\ \+$//g'.