Kernel: Use Userspace<T> for the waitid syscall

Kernel/API/Syscall.h

@@ -427,7 +427,7 @@ struct SC_unveil_params {
 struct SC_waitid_params {
     int idtype;
     int id;
-    struct siginfo* infop;
+    Userspace<struct siginfo*> infop;
     int options;
 };
 

Kernel/Process.h

@@ -222,7 +222,7 @@ public:
     int sys$kill(pid_t pid, int sig);
     [[noreturn]] void sys$exit(int status);
     int sys$sigreturn(RegisterState& registers);
-    pid_t sys$waitid(const Syscall::SC_waitid_params*);
+    pid_t sys$waitid(Userspace<const Syscall::SC_waitid_params*>);
     void* sys$mmap(const Syscall::SC_mmap_params*);
     int sys$munmap(void*, size_t size);
     int sys$set_mmap_name(const Syscall::SC_set_mmap_name_params*);

Kernel/Syscalls/waitid.cpp

@@ -93,7 +93,7 @@ KResultOr<siginfo_t> Process::do_waitid(idtype_t idtype, int id, int options)
     }
 }
 
-pid_t Process::sys$waitid(const Syscall::SC_waitid_params* user_params)
+pid_t Process::sys$waitid(Userspace<const Syscall::SC_waitid_params*> user_params)
 {
     REQUIRE_PROMISE(proc);