sparc64: Fix asm/percpu.h build error

In order to break a header dependency between lockdep and task_struct,
I need per-cpu stuff from lockdep.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Link: https://lkml.kernel.org/r/20200623083721.277992771@infradead.org

arch/sparc/include/asm/percpu_64.h

@@ -4,7 +4,9 @@
 
 #include <linux/compiler.h>
 
+#ifndef BUILD_VDSO
 register unsigned long __local_per_cpu_offset asm("g5");
+#endif
 
 #ifdef CONFIG_SMP
 

arch/sparc/include/asm/trap_block.h

@@ -2,6 +2,8 @@
 #ifndef _SPARC_TRAP_BLOCK_H
 #define _SPARC_TRAP_BLOCK_H
 
+#include <linux/threads.h>
+
 #include <asm/hypervisor.h>
 #include <asm/asi.h>