time_rz: avoid warning from bleeding-edge gcc's -Wnonnull Compiling with gcc version 6.0.0 20151017 (experimental) (GCC), I would see this: lib/time_rz.c: In function 'localtime_rz': lib/time_rz.c:292:15: error: nonnull argument 'tm' compared to NULL \ [-Werror=nonnull] if (tm && !save_abbr (tz, tm)) ^ That was complaining about "tm" because it is a parameter that was declared with the __nonnull__ attribute. * lib/time_rz.c (localtime_rz): Don't bother setting "tm" to the result of localtime_r.