Fix span size setting of SelReports and DecReports in HostBuffers
The span size of the SelReports and DecReports was set to the size in bytes, not the number of elements. This caused the safe_assign_to_host_buffer
function to not work properly if a memory region larger than the span size was to be copied. This MR fixes it and resolves MooreAnalysis#30 (closed), possibly also Moore#388 (closed)