Use gmtime_r() and localtime_r() instead of gmtime() and localtime().

plugins/sudoers/timestr.c

@@ -37,13 +37,13 @@ char *
 get_timestr(time_t tstamp, int log_year)
 {
     static char buf[128];
-    struct tm *timeptr;
+    struct tm tm;
 
-    if ((timeptr = localtime(&tstamp)) != NULL) {
+    if (localtime_r(&tstamp, &tm) != NULL) {
 	/* strftime() does not guarantee to NUL-terminate so we must check. */
 	buf[sizeof(buf) - 1] = '\0';
 	if (strftime(buf, sizeof(buf), log_year ? "%h %e %T %Y" : "%h %e %T",
-	    timeptr) != 0 && buf[sizeof(buf) - 1] == '\0')
+	    &tm) != 0 && buf[sizeof(buf) - 1] == '\0')
 	    return buf;
     }
     return NULL;