libbb: introduce and use xgettimeofday(), do not truncate 64-bit time_t in shells

function                                             old     new   delta
xgettimeofday                                          -      11     +11
get_local_var_value                                  280     281      +1
svlogd_main                                         1323    1322      -1
change_epoch                                          67      66      -1
timestamp_and_log                                    461     458      -3
hwclock_main                                         301     298      -3
fmt_time_bernstein_25                                135     132      -3
step_time                                            331     326      -5
script_main                                         1207    1202      -5
machtime                                              34      28      -6
curtime                                               61      54      -7
ts_main                                              423     415      -8
nmeter_main                                          761     751     -10
gettime1900d                                          67      46     -21
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/12 up/down: 12/-73)           Total: -61 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 598f28d..6ddfd77 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -842,7 +842,7 @@
 #if ENABLE_FEATURE_SYSLOGD_PRECISE_TIMESTAMPS
 	if (!timestamp) {
 		struct timeval tv;
-		gettimeofday(&tv, NULL);
+		xgettimeofday(&tv);
 		now = tv.tv_sec;
 		timestamp = ctime(&now) + 4; /* skip day of week */
 		/* overwrite year by milliseconds, zero terminate */