This commit adds a bunch of RPC calls, mostly XNU trap calls (calls that go directly to duct-taped XNU Mach trap calls).
The wrapper generator can now automatically generate server-side wrapper/boilerplate code these XNU trap calls.
These calls have not yet been tested and some (most of the non-IPC calls) probably require functions that haven't been implemented yet.
Implement some general RPC calls (corresponding to calls from the LKM): mach_port_deallocate, thread_set_handles, uidgid (a combination of get_uidgid and set_uidgid), and vchroot.
Additionally, we now have some RPC calls that do pass descriptors. Surprisingly, the code I had previously written was *almost* functional (just 2 minor generation and compilation errors). However, that code has now been tested for sending FDs from clients to the server, not vice versa, so that other direction might have issues.
Additionally, a few fixes have been made in the duct-tape code. For example, tasks now handle audit and security tokens like we used to do in the LKM. They also properly initialize and destroy their semaphore queues. Both threads and tasks now properly free their allocated structures.
More importantly, threads and tasks are now properly destroyed. In order to do this, a "kernel" microthread had to be introduced to perform "kernel" work from the managing code (since certain duct-tape destruction operations expect to be running in a microthread context). Additionally, this had to be an additional microthread because the managing code can't use thread calls, since those already expect a microthread context.
The Server can now easily monitor arbitrary descriptors using Monitors. Process monitoring has been converted to this system as well.
Most importantly, however, is that we can now detect `execve`s. libsystem_kernel opens a close-on-exec pipe and sends the read end to the server. When `execve` succeeds, the pipe is simply closed. When `execve` fails, libsystem_kernel writes a single byte to the pipe and then closes it. On the server side, we listen for a hang-up (this indicates the write end of the pipe has been closed). If we are able to read a byte, we know the execve failed; otherwise, if we read nothing (EOF), then we know it succeeded.
Together with changes in libsystem_kernel, this commit allows startup to progress to vchroot doing its thing (vchrooting) and then executing launchd. launchd then proceeds to die when trying to open a kqueue (as this still uses the LKM API).
Most of the newly added functions are just stubs for MIG calls. However, we now properly initialize IPC and related subsystems and we now have copyin/copyout that allows basic `mach_msg_overwrite_trap` usage.
dyld now progresses to `getHostInfo` and successfully retrieves `host_info` with a kernel MIG call (and then proceeds to die on `mach_port_deallocate`, since it hasn't been updated yet).
