bugfix - fixed regression error due to selectdata and cfg.avgovertime when there is no time in the input data, it was detected by test_bug1775.m


git-svn-id: svn+ssh://svn.fcdonders.nl/home/svnroot/fieldtrip/trunk@10081 0cf7c7f0-3615-4144-b4e6-68da3bce3cd0