IN C23, thread_local is a reserved keyword and we shall therefore
do nothing to redefine it. glibc has it defined for older standard
version with the right conditions.
v2 by Yu Watanabe:
Move the definition to missing_threads.h like the way we define e.g.
missing syscalls or missing definitions, and include it by the users.
Co-authored-by: Yu Watanabe <watanabe.yu+github@gmail.com>
We checked ERRNO_IS_NOT_SUPPORTED on a possible positive non-error code,
which isn't right.
Fix that. Also add caching, since we are about to call this more often.
Zbigniew Jędrzejewski-Szmek
Cristian RodríguezandYu Watanabe
Lennart Poettering