Kernel: Convert some more syscalls to Userspace<T>

These are really straightforward when all the helpers just work.

Kernel/Process.h

@@ -263,16 +263,16 @@ public:
     int sys$setresuid(uid_t, uid_t, uid_t);
     int sys$setresgid(gid_t, gid_t, gid_t);
     unsigned sys$alarm(unsigned seconds);
-    int sys$access(const char* pathname, size_t path_length, int mode);
+    int sys$access(Userspace<const char*> pathname, size_t path_length, int mode);
     int sys$fcntl(int fd, int cmd, u32 extra_arg);
     int sys$ioctl(int fd, unsigned request, FlatPtr arg);
-    int sys$mkdir(const char* pathname, size_t path_length, mode_t mode);
+    int sys$mkdir(Userspace<const char*> pathname, size_t path_length, mode_t mode);
     clock_t sys$times(tms*);
     int sys$utime(Userspace<const char*> pathname, size_t path_length, Userspace<const struct utimbuf*>);
     int sys$link(const Syscall::SC_link_params*);
     int sys$unlink(const char* pathname, size_t path_length);
     int sys$symlink(const Syscall::SC_symlink_params*);
-    int sys$rmdir(const char* pathname, size_t path_length);
+    int sys$rmdir(Userspace<const char*> pathname, size_t path_length);
     int sys$mount(const Syscall::SC_mount_params*);
     int sys$umount(const char* mountpoint, size_t mountpoint_length);
     int sys$chmod(const char* pathname, size_t path_length, mode_t);

Kernel/Syscalls/access.cpp

@@ -30,7 +30,7 @@
 
 namespace Kernel {
 
-int Process::sys$access(const char* user_path, size_t path_length, int mode)
+int Process::sys$access(Userspace<const char*> user_path, size_t path_length, int mode)
 {
     REQUIRE_PROMISE(rpath);
     auto path = get_syscall_path_argument(user_path, path_length);

Kernel/Syscalls/mkdir.cpp

@@ -30,7 +30,7 @@
 
 namespace Kernel {
 
-int Process::sys$mkdir(const char* user_path, size_t path_length, mode_t mode)
+int Process::sys$mkdir(Userspace<const char*> user_path, size_t path_length, mode_t mode)
 {
     REQUIRE_PROMISE(cpath);
     auto path = get_syscall_path_argument(user_path, path_length);

Kernel/Syscalls/rmdir.cpp

@@ -30,7 +30,7 @@
 
 namespace Kernel {
 
-int Process::sys$rmdir(const char* user_path, size_t path_length)
+int Process::sys$rmdir(Userspace<const char*> user_path, size_t path_length)
 {
     REQUIRE_PROMISE(cpath);
     auto path = get_syscall_path_argument(user_path, path_length);