[example2_filter] Removing build-generated files

Signed-off-by: Edoardo Paone <edoardo.paone@polimi.it>
[example2_filter] Fixed kernel template

Output buffer passed as argument to the kernel is global.

Signed-off-by: Edoardo Paone <edoardo.paone@polimi.it>
[opencl] Fixed version check in Haskell makefile

Signed-off-by: Edoardo Paone <edoardo.paone@polimi.it>
Merge pull request #1 from paone/master

WIP - Minor fix