It does not make sense to define e.g. HAVE_CUSPARSE when HAVE_CUDA is
not defined. Otherwise it would be necessary to pass the CUDA's include
path even when compiling with GCC without CUDA support.

RowLengths was renamed to CompressedRowsLengths.
OpenMP support wads added to matrix-vector multiplication and to scalar
products.
CSR format can use Cusparse for SpMV.

Fixing timers.