gh-120593: Fix const qualifier in pyatomic.h

[vstinner]

• Issue: pyatomic_gcc.h with GCC discards const qualifier #120593

[vstinner]

This PR fix the following warnings:

/home/vstinner/python/main/Include/cpython/pyatomic_gcc.h: In function ‘_Py_atomic_load_ptr’: /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h:300:34: error: cast discards ‘const’ qualifier from pointer target type [-Werror=cast-qual] 300 |{return (void *)__atomic_load_n((void **)obj, __ATOMIC_SEQ_CST)} | ^ /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h: In function ‘_Py_atomic_load_ptr_relaxed’: /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h:359:34: error: cast discards ‘const’ qualifier from pointer target type [-Werror=cast-qual] 359 |{return (void *)__atomic_load_n((const void **)obj, __ATOMIC_RELAXED)} | ^ /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h:359:10: error: cast discards ‘const’ qualifier from pointer target type [-Werror=cast-qual] 359 |{return (void *)__atomic_load_n((const void **)obj, __ATOMIC_RELAXED)} | ^ /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h: In function ‘_Py_atomic_load_ptr_acquire’: /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h:493:34: error: cast discards ‘const’ qualifier from pointer target type [-Werror=cast-qual] 493 |{return (void *)__atomic_load_n((void **)obj, __ATOMIC_ACQUIRE)} | ^ /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h: In function ‘_Py_atomic_load_uintptr_acquire’: /home/vstinner/python/main/Include/cpython/pyatomic_gcc.h:497:37: error: cast discards ‘const’ qualifier from pointer target type [-Werror=cast-qual] 497 |{return (uintptr_t)__atomic_load_n((uintptr_t *)obj, __ATOMIC_ACQUIRE)} | ^ cc1: all warnings being treated as errors error: command '/usr/bin/gcc' failed with exit code 1 

[vstinner]

My previous attempt using (const void * const *) cast didn't work well. The correct cast is to (void * const *).

[colesbury]

LGTM!

[miss-islington-app]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

[bedevere-app]

GH-121057 is a backport of this pull request to the 3.13 branch.