posix: Fix pthread_once has incorrect behavior

As described in
https://pubs.opengroup.org/onlinepubs/7908799/xsh/pthread_once.html.
The behavior of pthread_once() is undefined if once_control has
automatic storage duration or is not initialized by PTHREAD_ONCE_INIT

However, in Zephyr, the implementation is incorrect. If the init value
is PTHREAD_ONCE_INIT, the program will never run the init_func.

Signed-off-by: Jaxson Han <jaxson.han@arm.com>
3 files changed