time: remove unused var warning in example.

time: remove unused var warning in example.

Compiler:
/home/rusty/devel/cvs/ccan/ccan/time/time.h: In function ‘main’:
/home/rusty/devel/cvs/ccan/ccan/time/time.h:334:16: warning: variable ‘tv’ set but not used [-Wunused-but-set-variable]

Compiler:
/home/rusty/devel/cvs/ccan/ccan/time/time.h: In function ‘main’:
/home/rusty/devel/cvs/ccan/ccan/time/time.h:353:17: warning: variable ‘ts’ set but not used [-Wunused-but-set-variable]

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>