commit 98ca73bfe3f574ba72232013919885bdae679e09
Author: Daniel Kolesa <daniel@octaforge.org>
Date:   Fri Sep 23 03:55:45 2022 +0200

    use posix as a fallback for aligned_alloc
    
    Testing for feature test macros is a broken antipattern, and
    fucks up in ugly ways under musl. Since we don't really care
    for having a non-POSIX fallback, always use the POSIX code
    unless forced.

diff --git a/boost/align/aligned_alloc.hpp b/boost/align/aligned_alloc.hpp
index 1d81a13..f2b5137 100644
--- a/boost/align/aligned_alloc.hpp
+++ b/boost/align/aligned_alloc.hpp
@@ -38,10 +38,8 @@ Distributed under the Boost Software License, Version 1.0.
 #include <boost/align/detail/aligned_alloc_posix.hpp>
 #elif defined(sun) || defined(__sun)
 #include <boost/align/detail/aligned_alloc_sunos.hpp>
-#elif (_POSIX_C_SOURCE >= 200112L) || (_XOPEN_SOURCE >= 600)
-#include <boost/align/detail/aligned_alloc_posix.hpp>
 #else
-#include <boost/align/detail/aligned_alloc.hpp>
+#include <boost/align/detail/aligned_alloc_posix.hpp>
 #endif
 
 #endif