Capability checking added as compiling code.

Capability checking for thread_control, exregs, mutex, cap_control,
ipc, and map system calls.

The visualised model is implemented in code that compiles, but
actual functionality hasn't been tested.

Need to add:
- Dynamic assignment of initial resources matching with what's
defined in the configuration.
- A paged-thread-group, since that would be a logical group of
seperation from a capability point-of-view.
- Resource ids for various tasks. E.g.
  - Memory capabilities don't have target resources.
  - Thread capability assumes current container for THREAD_CREATE.
  - Mutex syscall assumes current thread (this one may not need
    any changing)
  - cap_control syscall assumes current thread. It may happen to
    be that another thread's capability list is manipulated.

Last but not least:
- A simple and easy-to-use userspace library for dynamic expansion
  of resource domains as new resources are created such as threads.

include/l4/api/syscall.h

@@ -40,7 +40,7 @@ int sys_unmap(unsigned long virtual, unsigned long npages, unsigned int tid);
 int sys_space_control(void);
 int sys_ipc_control(void);
 int sys_map(unsigned long phys, unsigned long virt, unsigned long npages,
-	    unsigned long flags, unsigned int tid);
+	    unsigned int flags, l4id_t tid);
 int sys_getid(struct task_ids *ids);
 int sys_capability_control(unsigned int req, unsigned int flags, void *addr);
 int sys_container_control(unsigned int req, unsigned int flags, void *addr);