um: kill HOST_TASK_PID

just provide get_current_pid() to the userland side of things
instead of get_current() + manual poking in its results

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/process.c

@@ -126,9 +126,9 @@ void exit_thread(void)
 {
 }
 
-void *get_current(void)
+int get_current_pid(void)
 {
-	return current;
+	return task_pid_nr(current);
 }
 
 /*