um: Fix naming clash between UML and scheduler

__cant_sleep was already used and exported by the scheduler.
The name had to be changed to a UML specific one.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Reviewed-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/include/shared/kern_util.h

@@ -50,7 +50,7 @@ extern void do_uml_exitcalls(void);
  * Are we disallowed to sleep? Used to choose between GFP_KERNEL and
  * GFP_ATOMIC.
  */
-extern int __cant_sleep(void);
+extern int __uml_cant_sleep(void);
 extern int get_current_pid(void);
 extern int copy_from_user_proc(void *to, void *from, int size);
 extern char *uml_strdup(const char *string);