Print a "Gen" line when generating a file

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/Makefile b/tests/Makefile
index 01f349e..e07ac61 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -56,6 +56,7 @@
 GENERATED_FILES += src/test_keys.h src/test_certs.h
 
 opt-testcases/tls13-compat.sh: scripts/generate_tls13_compat_tests.py
+	echo "  Gen   $@"
 	$(PYTHON) scripts/generate_tls13_compat_tests.py -o $@
 GENERATED_FILES += opt-testcases/tls13-compat.sh
 
@@ -153,9 +154,11 @@
 
 src/test_certs.h: ../framework/scripts/generate_test_cert_macros.py \
 				  $($(PYTHON) ../framework/scripts/generate_test_cert_macros.py --list-dependencies)
+	echo "  Gen   $@"
 	$(PYTHON) ../framework/scripts/generate_test_cert_macros.py --output $@
 
 src/test_keys.h: ../framework/scripts/generate_test_keys.py
+	echo "  Gen   $@"
 	$(PYTHON) ../framework/scripts/generate_test_keys.py --output $@
 
 TEST_OBJS_DEPS = $(wildcard include/test/*.h include/test/*/*.h)