patch 9.0.1651: unclear why syntax test fails on Mac

Problem:    Unclear why syntax test fails on Mac.
Solution:   Temporarily show the whole "messages" file.
diff --git a/runtime/syntax/Makefile b/runtime/syntax/Makefile
index a52c7d6..c8a7f00 100644
--- a/runtime/syntax/Makefile
+++ b/runtime/syntax/Makefile
@@ -26,7 +26,9 @@
 	@echo "../$(VIMPROG)" > testdir/vimcmd
 	@echo "$(RUN_VIMTEST)" >> testdir/vimcmd
 	VIMRUNTIME=$(VIMRUNTIME) $(VIMPROG) --clean --not-a-term $(DEBUGLOG) -u testdir/runtest.vim
-	@tail -n 6 testdir/messages
+	@# FIXME: Temporarily show the whole file to find out what goes wrong
+	@#tail -n 6 testdir/messages
+	@cat testdir/messages
 
 
 clean testclean: