cpp: Fix "make check" by defining a comparator for "Empty"

The TCompactProtocol revision added a "set<Empty>" in DebugProtoTest.
C++ needs a comparator in order to link this.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@743111 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/test/Makefile.am b/test/Makefile.am
index 5f2ce8d..cc92ce0 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -19,7 +19,8 @@
 	gen-cpp/ThriftTest_constants.cpp \
 	gen-cpp/ThriftTest.cpp \
 	gen-cpp/ThriftTest_types.cpp \
-	ThriftTest_extras.cpp
+	ThriftTest_extras.cpp \
+	DebugProtoTest_extras.cpp
 
 libtestgencpp_la_LIBADD = $(top_builddir)/lib/cpp/libthrift.la