fhem.pl: add constants (Forum #96959)

git-svn-id: https://svn.fhem.de/fhem/trunk@18497 2b470e98-0d58-463d-a4d8-8e2adae1ed80

fhem/fhem.pl

@@ -270,6 +270,11 @@ use vars qw(@authorize);        # List of authorization devices
 use vars qw(@intAtA);           # Internal timer array
 use vars qw(@structChangeHist); # Contains the last 10 structural changes
 
+use constant {
+  DAYSECONDS    => 86400,
+  HOURSECONDS   =>  3600,
+  MINUTESECONDS =>    60
+};
 
 $selectTimestamp = gettimeofday();
 $cvsid = '$Id$';