lockdep: fix unused function warning in kernel/lockdep.c

Impact: fix build warning

this warning:

kernel/lockdep.c:584: warning: ‘print_lock_dependencies’ defined but not used

triggers because print_lock_dependencies() is only used if both
CONFIG_TRACE_IRQFLAGS and CONFIG_PROVE_LOCKING are enabled.

But adding #ifdefs is not an option here - it would spread out to 4-5
other helper functions and uglify the file. So mark this function
as __used - it's static and the compiler can eliminate it just fine.

Signed-off-by: Ingo Molnar <[e-mail]>

kernel/lockdep.c

···
 /*
  * printk all lock dependencies starting at <entry>:
  */
-static void print_lock_dependencies(struct lock_class *class, int depth)
+static void __used
+print_lock_dependencies(struct lock_class *class, int depth)
 {
 	struct lock_list *entry;