vdso: don't forget to adjust vma_area_list->nr

A proxy vdso is removed from the vma_area_list list,
so vma_area_list->nr must be decremented.

Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/x86/vdso.c

@@ -145,6 +145,7 @@ int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
 			 (long)vma->e->start);
 		list_del(&marked->list);
 		xfree(marked);
+		vma_area_list->nr--;
 	}
 	ret = 0;
 err: