fixed openni 2.1 header for Linux
fixed openni 2.1 header for Linux

Signed-off-by: Richard Newcombe <ec94511634641cadaefeddfbee479d77c6963ba2@gmail.com>

mp3guy/Pangolin,tschmidt23/Pangolin,visigoth/Pangolin,mp3guy/Pangolin,mp3guy/Pangolin,pinglin/Pangolin,randi120/Pangolin,arpg/Pangolin,visigoth/Pangolin,tschmidt23/Pangolin,renzodenardi/Pangolin,stevenlovegrove/Pangolin,stevenlovegrove/Pangolin,stevenlovegrove/Pangolin,pinglin/Pangolin,wxdzju/Pangolin,randi120/Pangolin,wxdzju/Pangolin,arpg/Pangolin,renzodenardi/Pangolin,tschmidt23/Pangolin