supress echoing of for loop

Makefile

@@ -165,7 +165,7 @@ test/addons/.buildstamp: config.gypi \
  test/addons/.docbuildstamp
 # Cannot use $(wildcard test/addons/*/) here, it's evaluated before
 # embedded addons have been generated from the documentation.
- for dirname in test/addons/*/; do \
+ @for dirname in test/addons/*/; do \
  echo "\nBuilding addon $$PWD/$$dirname" ; \
  env MAKEFLAGS="-j1" $(NODE) deps/npm/node_modules/node-gyp/bin/node-gyp \
  --loglevel=$(LOGLEVEL) rebuild \