Channel 8 RMA corruption fix
Adjust the workspace definitions so that Instance0 has the same address/offset as End_Of_Code, and so that WorkSpaceSize has the value Instance0 + 8*4.
The previous version of the code made the false assumption that the AmountToCopy and WorkSpaceSize definitions wouldn't add anything to the output binary. This resulted in WorkSpaceSize being 4 bytes larger than strictly necessary (due to AmountToCopy before it), but more dangerously, Instance0 was placed 8 bytes after End_Of_Code, causing the code to write off the end of the heap block if the voice is assigned to channel 8.
Fixes https://www.riscosopen.org/tracker/tickets/505 (StringLib variant)