The jemalloc memory allocator likes to bypass the libc when calling write, so
it calls the syscall directly. Let's make write available through this interface
as well.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>