Heed --quiet when running make generated_files

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 4614029..c3df05b 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -713,7 +713,11 @@
     # since make doesn't have proper dependencies, remove any possibly outdate
     # file that might be around before generating fresh ones
     make neat
-    make generated_files
+    if [ $QUIET -eq 1 ]; then
+        make -s generated_files
+    else
+        make generated_files
+    fi
 }