runtime(indent-tests): GitHub Actions doesn't show why indent tests failed

Problem:  GitHub Actions doesn't show why indent tests failed
Solution: Send the .fail files to stdout

References:
https://github.com/vim/vim/pull/16852#issuecomment-2719041781

closes: #16870

Signed-off-by: David Mandelberg <david@mandelberg.org>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/indent/Makefile b/runtime/indent/Makefile
index 2af1276..742e43f 100644
--- a/runtime/indent/Makefile
+++ b/runtime/indent/Makefile
@@ -10,7 +10,16 @@
 # If a test succeeds a testdir/*.out file will be written.
 # If a test fails a testdir/*.fail file will be written.
 test:
-	VIMRUNTIME=$(VIMRUNTIME) $(VIMPROG) --clean --not-a-term -u testdir/runtest.vim
+	VIMRUNTIME=$(VIMRUNTIME) $(VIMPROG) --clean --not-a-term -u testdir/runtest.vim || \
+		{ \
+			retval=$$?; \
+			for fail in testdir/*.fail; do \
+				[ -f "$$fail" ] || continue; \
+				echo "$$fail:"; \
+				cat "$$fail"; \
+			done; \
+			exit $$retval; \
+		}
 	@echo "INDENT TESTS: DONE"