pyatomic include statement shouldn't use "cpython/*" but just "*"

[timprepscius]

Bug report

Bug description:

I'm looking at (and using) a build generated from:

  git clone --depth 1 https://github.com/python/cpython.git --branch v3.13.1

  pushd cpython

    ./configure --enable-optimizations --prefix=$(pwd)/install
    make -j4
    make install

  popd

in the file: cpython/install/include/python3.13/cpython/pyatomic.h

there is the statement

#if _Py_USE_GCC_BUILTIN_ATOMICS
#  define Py_ATOMIC_GCC_H
#  include "cpython/pyatomic_gcc.h"
#  undef Py_ATOMIC_GCC_H
#elif __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__)
#  define Py_ATOMIC_STD_H
#  include "cpython/pyatomic_std.h"
#  undef Py_ATOMIC_STD_H
#elif defined(_MSC_VER)
#  define Py_ATOMIC_MSC_H
#  include "cpython/pyatomic_msc.h"
#  undef Py_ATOMIC_MSC_H
#else
#  error "no available pyatomic implementation for this platform/compiler"
#endif

these includes say: include, relative to me (quotation), the file cpython/pyatomic_gcc.h

But there is no file "cpython/pyatomic_gcc.h" relative to the cypthon/pyatomic.h

I can of course compensate by putting a:
ln -s . cypthon
in that cpython directory

The fix is to change "cpython/pyatomic_gcc.h" to "pyatomic_gcc.h"
where quotation = "relative to me"

CPython versions tested on:

3.13

Operating systems tested on:

No response

Linked PRs

• gh-129296: Fix pyatomic.h include paths #129320

[ZeroIntensity]

The compiler should be falling back to the include path regardless--there's no actual compile error in practice, is there?

cc @colesbury