Improve updating of test/Makefile for out-of-dir builds.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@91854 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile b/Makefile
index 9002123..8d3fa29 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@
 include $(LEVEL)/Makefile.common
 
 ifneq ($(PROJ_SRC_ROOT),$(PROJ_OBJ_ROOT))
-all::
+$(RecursiveTargets)::
 	$(Verb) if [ ! -f test/Makefile ]; then \
 	  $(MKDIR) test; \
 	  $(CP) $(PROJ_SRC_DIR)/test/Makefile test/Makefile; \