Because some systems may not have all the available data we should
check if the data exists before trying to display it.

To test:
Before patch change the line in lib/mahara.php
 if (function_exists('posix_times')) {
to
 if (!function_exists('posix_times')) {

and make sure the 'perf_to_log' config option is set to true

This will cause the errors we are trying to deal with to show up

behatnotneeded

Change-Id: If9610fa0eaf4c8bb036b21c1c75e10d828de7934
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>