workaround: NVCC does not compile Kernel

 - in the else-branch of a #ifdef __CUDA_ARCH__, nvcc ignores the
   existing kernels, resulting in a crash
 - see 185669b367c8502278a8cb4f9cf824ccdcf6aca4 for a demonstration of
   the bug
 - in this fix, the function must be explicitly called to work around
   implementation details of templated inheritance (see policy based
   design: policy member functions are not compiled if they are not in
   use)

Conflicts:

	src/include/scatteralloc/policy_malloc_hostclass.hpp
Merge pull request #49 from slizzered/bugfix-get_available_slots_host

workaround: NVCC does not compile Kernel