THRIFT-3711 Add D to cross language test

This closes #923
diff --git a/lib/d/Makefile.am b/lib/d/Makefile.am
index 30b5eb3..5c529ba 100644
--- a/lib/d/Makefile.am
+++ b/lib/d/Makefile.am
@@ -185,6 +185,8 @@
 TESTS = $(addprefix unittest/debug/, $(d_test_modules)) \
 	$(addprefix unittest/release/, $(d_test_modules))
 
+precross: all-local
+	$(MAKE) -C test precross
 
 EXTRA_DIST = \
 	src \