ANDROID: mm: omm: Provide prototype for exported dump_tasks()

Commit 0fcb70851f ("Makefile.extrawarn: turn on missing-prototypes
globally") enabled warnings for all missing prototypes which causes
errors due to the fact that we have -Werror enabled.

Provide missing prototype for exported dump_tasks() function in
order to avoid the following build errors:

  mm/oom_kill.c:424:6:
    error: no previous prototype for 'dump_tasks' [-Werror=missing-prototypes]

Fixes: 4df28ddcd9 ("ANDROID: mm: export dump_tasks symbol.")
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Ifb6e4997cef108c8b037ce6530c7b9beedb24b7b

include/linux/oom.h

@@ -110,6 +110,8 @@ extern int unregister_oom_notifier(struct notifier_block *nb);
 extern bool oom_killer_disable(signed long timeout);
 extern void oom_killer_enable(void);
 
+extern void dump_tasks(struct oom_control *oc);
+
 extern struct task_struct *find_lock_task_mm(struct task_struct *p);
 
 #endif /* _INCLUDE_LINUX_OOM_H */