x86/vdso: Ensure all kernel code is seen by objtool

extable.c is kernel code and not part of the VDSO
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111143.512144110@infradead.org

arch/x86/entry/vdso/Makefile

@@ -33,11 +33,12 @@ vobjs32-y += vdso32/vclock_gettime.o
 vobjs-$(CONFIG_X86_SGX)	+= vsgx.o
 
 # files to link into kernel
-obj-y				+= vma.o extable.o
-KASAN_SANITIZE_vma.o		:= y
-UBSAN_SANITIZE_vma.o		:= y
-KCSAN_SANITIZE_vma.o		:= y
-OBJECT_FILES_NON_STANDARD_vma.o	:= n
+obj-y					+= vma.o extable.o
+KASAN_SANITIZE_vma.o			:= y
+UBSAN_SANITIZE_vma.o			:= y
+KCSAN_SANITIZE_vma.o			:= y
+OBJECT_FILES_NON_STANDARD_vma.o		:= n
+OBJECT_FILES_NON_STANDARD_extable.o	:= n
 
 # vDSO images to build
 vdso_img-$(VDSO64-y)		+= 64