Fix a parallel build bug under test

The "_extras.cpp" files depend on the appropriate ".h" files,
but that dependency is not listed in the Makefile, and cannot
be determined automatically by automake because the .h files
are generated.  Add explicit dependencies so "make -j8 check"
works.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@756353 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/test/Makefile.am b/test/Makefile.am
index b1092d5..1a2884e 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -20,6 +20,9 @@
 	ThriftTest_extras.cpp \
 	DebugProtoTest_extras.cpp
 
+ThriftTest_extras.o: gen-cpp/ThriftTest_types.h
+DebugProtoTest_extras.o: gen-cpp/DebugProtoTest_types.h
+
 libtestgencpp_la_LIBADD = $(top_builddir)/lib/cpp/libthrift.la
 
 noinst_PROGRAMS = Benchmark