build: do not ignore errors during build-addons

Errors during build-addons were being silently ignored.

PR-URL: https://github.com/nodejs/node/pull/5494
Reviewed-By: bnoordhuis - Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: targos - Michaël Zasso <mic.besace@gmail.com>

Makefile

@@ -144,7 +144,7 @@ test/addons/.buildstamp: $(ADDONS_BINDING_GYPS) | test/addons/.docbuildstamp
 	for dirname in test/addons/*/; do \
 		$(NODE) deps/npm/node_modules/node-gyp/bin/node-gyp rebuild \
 			--directory="$$PWD/$$dirname" \
-			--nodedir="$$PWD"; \
+			--nodedir="$$PWD" || exit 1 ; \
 	done
 	touch $@