ACC: Make header files usable for C and C++.

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13841 bac0169d-1eea-4375-b5f6-f89d2ced9994
makedep: Add Python 2.4 compatibility

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@13842 bac0169d-1eea-4375-b5f6-f89d2ced9994
Add first version of OpenCL backend. Events are not finished yet.