The GPU stdio functions were depending on indirect inclusion for some of
their dependencies. This patch should fix all of that.

This is a part of #97655.

Reverts llvm/llvm-project#98075

bots are broken

This is a part of #97655.

reland of https://github.com/llvm/llvm-project/pull/98215

Additionally adds proxy headers for FILE and the fopencookie types

The arm32 build has been failing due to redefinitions of the off_t type.
This patch fixes this by moving off_t to a proper proxy header. To do
this, it also moves stdio macros to a proxy header to hopefully avoid
including this proxy header alongside this public stdio.h.

This is step 4 of
https://discourse.llvm.org/t/rfc-customizable-namespace-to-allow-testing-the-libc-when-the-system-libc-is-also-llvms-libc/73079

The GPU has much tighter requirements for handling IO functions.
Previously we attempted to define the GPU as one of the platform files.
Using a common interface allowed us to easily define these functions
without much extra work. However, it became more clear that this was a
poor fit for the GPU. The file interface uses function pointers, which
prevented inlining and caused bad perfromance and resource usage on the
GPU. Further, using an actual `FILE` type rather than referring to it as
a host stub prevented us from usin files coming from the host on the GPU
device.

After talking with @sivachandra, the approach now is to simply define
GPU specific versions of the functions we intend to support. Also, we
are ignoring `errno` for the time being as it is unlikely we will ever
care about supporting it fully.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D157427