THRIFT-3711 Add D to cross language test

This closes #923
diff --git a/lib/Makefile.am b/lib/Makefile.am
index e699b9f..cb8d290 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -75,6 +75,7 @@
 
 if WITH_D
 SUBDIRS += d
+PRECROSS_TARGET += precross-d
 endif
 
 if WITH_NODEJS