Finally simplify the time calculations!

According to

   http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap01.html

a shell must be able to do modulus (=remainder). Zsh, bash and dash
confirm this and thus I can save another line and get rid of a very
ugly one.

Signed-off-by: Nico Schottelius <nico@ikn.schottelius.org>

ccollect.sh

@@ -560,14 +560,14 @@ while [ "${source_no}" -lt "${no_sources}" ]; do
       fi
    fi
 
-   # Calculation
+   #
+   # Time calculation
+   #
    end_s="$(${SDATE})"
-
    full_seconds="$((${end_s} - ${begin_s}))"
    hours="$((${full_seconds} / 3600))"
-   seconds="$((${full_seconds} - (${hours} * 3600)))"
-   minutes="$((${seconds} / 60))"
-   seconds="$((${seconds} - (${minutes} * 60)))"
+   minutes="$(((${full_seconds} % 3600) / 60))"
+   seconds="$((${full_seconds} % 60))"
 
    _techo "Backup lasted: ${hours}:${minutes}:${seconds} (h:m:s)"
 ) | add_name