ruvm 0.5.1

This patch starts M7 with a working qemu-x86_64, and moves M6 along with virtio-gpu, a VNC server, the input layer and the audio core.

For M7: qemu-x86_64 now runs static and dynamic x86_64 Linux programs on an x86_64 Linux host, with the ELF loader, the guest address space and mmap engine from QEMU's mmap.c, the cpu loop and the common syscalls (#197). On 46 programs, including static and dynamic hello, about 30 busybox applets with sh doing fork, exec and pipes, coreutils, dash and the segfault, abort and ud2 crash paths, stdout, stderr and the exit status match QEMU 11.1's qemu-x86_64. Signal handlers are recorded but not run yet, threads are refused, there is no vDSO, and -g, -strace and the other guest debug options are refused with a message.

For M6: there is virtio-gpu 2D as virtio-gpu-pci and virtio-gpu-device, and a VNC server with -vnc, -display vnc=, RFB 3.3 to 3.8, VNC auth and the raw, hextile, zlib and tight encodings (#196). On x86, 30 of 30 virtio-gpu screendumps and 112 of 112 VNC frames are byte for byte the same as QEMU's. The input layer from ui/input.c is in, with send-key, input-send-event, query-mice and -k, and the PS/2 keyboard and mouse and the VNC server are wired into it (#199). All 38 input checks against QEMU, over QMP and two VNC clients, match on the serial bytes the guest saw and every byte the clients got. The audio core from QEMU's audio/ is in with the mixing engine and resampler, -audiodev and -audio, query-audiodevs and the none and wav backends (#198). There are no sound cards yet, those come next.