This uses some definitions from <sys/cdefs.h> in gcc 8.4.0, not present
in musl or gcc11.
Also use clock_gettime() instead of syscall(__NR_clock_gettime,...),
which is not currently defined.
Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
(cherry picked from commit 281df4bcf5)