x86: no stack protector for vdso

Impact: avoid crash on vsyscall
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/vdso/Makefile

@@ -38,7 +38,7 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
 	$(call if_changed,objcopy)
 
 CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
-       $(filter -g%,$(KBUILD_CFLAGS))
+       $(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector)
 
 $(vobjs): KBUILD_CFLAGS += $(CFL)