Make PCI_RAMAlloc more robust
- Use the new OS_Memory 23 memory reservation system to stop other DAs claiming exclusive use of the physical memory we want to use for the PCI heap
- Switch to using the new OS_Heap 8 instead of OS_Heap 7, so that memory alignment can be handled in terms of physical address insead of logical address (avoiding the need to ensure the DA is both logically and physically aligned)
- Make sure the DA max size matches the amount of memory we found, so that if we can't get the full 32MB as desired, we don't run the risk of growing the DA into a non physically contiguous chunk of RAM
Requires RiscOS/Sources/Kernel!12 (merged) and RiscOS/Sources/Kernel!13 (merged)