build-sys: make vhost-user-scsi depend on libvhost-user.a

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/Makefile b/Makefile
index 64d3a9e..97b4508 100644
--- a/Makefile
+++ b/Makefile
@@ -480,7 +480,7 @@
 ivshmem-server$(EXESUF): $(ivshmem-server-obj-y) $(COMMON_LDADDS)
 	$(call LINK, $^)
 endif
-vhost-user-scsi$(EXESUF): $(vhost-user-scsi-obj-y)
+vhost-user-scsi$(EXESUF): $(vhost-user-scsi-obj-y) libvhost-user.a
 	$(call LINK, $^)
 
 module_block.h: $(SRC_PATH)/scripts/modules/module_block.py config-host.mak