lockdep: build fix for !PROVE_LOCKING

The __GFP_FS annotations fail to build with CONFIG_LOCKDEP=y,
CONFIG_PROVE_LOCKING=n, ammend that.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/lockdep.c

@@ -2396,6 +2396,10 @@ static inline int separate_irq_context(struct task_struct *curr,
 	return 0;
 }
 
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+}
+
 #endif
 
 /*