In TH1::BufferEmpty, one must call Reset with option "ICE" to avoid resetting

the list of functions when action = -1 (when called by THistPainter).
This solves https://savannah.cern.ch/bugs/?71251
and http://root.cern.ch/phpBB3/viewtopic.php?f=3&t=10973


git-svn-id: http://root.cern.ch/svn/root/trunk@34769 27541ba8-7e3a-0410-8455-c3a389f83636