Replace phony copy-bundle-assets target by a real one

This makes that we don't rerun the rule during
`domserver-install` if it already ran during `domserver`, so
that if you install as root, the local files are still owned
by the user who first ran `make domserver`, not root.

This does assume that if the directory `public/bundles/nelmioapidoc`
exists, then it contains the assets, and these won't automatically
get updated, for example, in the setting of a maintainer-install.

webapp/Makefile

@@ -43,20 +43,18 @@ composer-dump-autoload-dev:
 	@echo "# the DOMjudge Symfony application in developer mode. Adjust as needed." >> $@
 	@echo "APP_ENV=dev" >> $@
 
-copy-bundle-assets:
+public/bundles/nelmioapidoc:
 # We can not use bin/console here, as when using a fakeroot,
 # the include paths are broken. We just copy in the data we need
-	-rm -rf public/bundles/nelmioapidoc
-	mkdir -p public/bundles/nelmioapidoc
-	cp -a vendor/nelmio/api-doc-bundle/public/* public/bundles/nelmioapidoc/
+	-rm -rf $@
+	mkdir -p $@
+	cp -a vendor/nelmio/api-doc-bundle/public/* $@
 
 clean-l:
 	-rm -rf public/bundles/nelmioapidoc
 	-rm -f vendor/autoload_runtime.php
 
-domserver-l:
-# This must be done first to install with the rest.
-	$(MAKE) copy-bundle-assets
+domserver-l: public/bundles/nelmioapidoc
 
 install-domserver:
 	$(INSTALL_DIR) $(DESTDIR)$(domserver_webappdir);
@@ -88,5 +86,4 @@ maintainer-clean-l:
 		done ; \
 	done
 
-.PHONY: composer-dump-autoload composer-dump-autoload-dev \
-        copy-bundle-assets
+.PHONY: composer-dump-autoload-dev