Tweak Ruby Makefile to use --gen syntax


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@668889 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/test/rb/Makefile b/test/rb/Makefile
index 326f720..ed0f91b 100644
--- a/test/rb/Makefile
+++ b/test/rb/Makefile
@@ -12,8 +12,8 @@
 all: stubs tests
 
 stubs: ../ThriftTest.thrift ../SmallTest.thrift
-	$(THRIFT) --rb ../ThriftTest.thrift
-	$(THRIFT) --rb ../SmallTest.thrift
+	$(THRIFT) --gen rb ../ThriftTest.thrift
+	$(THRIFT) --gen rb ../SmallTest.thrift
 
 tests: stubs
 	ruby TestSuite.rb