Since include/net/ppp_defs.h is used in both kernelspace and userland
it is hard to include <time.h> there.
This commit fixes the problems in userspace code individually and leaves
ppp_defs.h as-is.
Signed-off-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>