Before the change described in
https://gcc.gnu.org/pipermail/gcc-patches/2023-September/631393.html it
appeared that inlining built-in GCC function __atomic_test_and_set() was
incorrect. It resulted in a non-atomic write.
For GCC toolchains which do not have such patch yet, this commit fixes
__atomic_test_and_set to be atomic in IDF's builds.
