FreeBSD doesn't use tar -c with -O

plugins/sfx.mk

@@ -38,8 +38,10 @@ endef
 
 sfx:
 	$(call render_template,sfx_stub,$(SFX_OUTPUT))
-	$(gen_verbose) tar -C $(RELX_OUTPUT_DIR) -czO $(RELX_RELEASE) >> $(SFX_OUTPUT)
+	$(gen_verbose) tar -C $(RELX_OUTPUT_DIR) -czf $(RELX_OUTPUT_DIR)/$(RELX_RELEASE).tgz $(RELX_RELEASE)
+	$(verbose) cat $(RELX_OUTPUT_DIR)/$(RELX_RELEASE).tgz >> $(SFX_OUTPUT)
 	$(verbose) chmod +x $(SFX_OUTPUT)
+	$(verbose) rm $(RELX_OUTPUT_DIR)/$(RELX_RELEASE).tgz
 
 endif
 endif