makefile: decompose deps installation

Since it will be more convenient to see CI jobs making its own work, the
installation of rocks was rewriten to install rocks only for one task.

Makefile

@@ -51,9 +51,24 @@ coveralls: $(LUACOV_STATS)
 	echo "Send code coverage data to the coveralls.io service"
 	luacov-coveralls --include ^roles --verbose --repo-token ${GITHUB_TOKEN}
 
-deps:
+deps-test:
 	tt rocks install luatest 1.0.1
-	tt rocks install luacheck 0.26.0
+
+deps-coverage: deps-test
 	tt rocks install luacov 0.13.0-1
 	tt rocks install luacov-coveralls 0.2.3-1 --server=http://luarocks.org
+
+deps-lint:
+	tt rocks install luacheck 0.26.0
+
+deps:
+ifeq ($(depname), test)
+	$(MAKE) deps-test
+else ifeq ($(depname), coverage)
+	$(MAKE) deps-coverage
+else ifeq ($(depname), lint)
+	$(MAKE) deps-lint
+else
+	$(MAKE) deps-coverage deps-lint
+endif
 	tt rocks make