Fix typos in GPU libc's documentation about the rpc implementation.

This reverts commit 2e145f11c0bcfa2052416d96d682c75f33971a8c.

Somehow causes some static assertions to fail?

Summary:
For purposes of determining the triple, it's more correct to use
`LLVM_DEFAULT_TARGET_TRIPLE`.

Summary:
This patch moves the RPC server handling to be a header only utility
stored in the `shared/` directory. This is intended to be shared within
LLVM for the loaders and `offload/` handling.

Generally, this makes it easier to share code without weird
cross-project binaries being plucked out of the build system. It also
allows us to soon move the loader interface out of the `libc` project so
that we don't need to bootstrap those and can build them in LLVM.

Summary:
These should allow us to build with locale support for libcxx.

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:
Since this was added the offloading target now requires `offload`.

Fixes: https://github.com/llvm/llvm-project/issues/127458

Summary:
Forgot to close it, that'll make it deadlock after awhile.

Summary:
This introduces libc cache files and adds one for building the GPU
support. The cache files will set defaults for these arguments which can
be overridden if the user needs to. They also serve as documentation for
how the builid is expected to look.