Move Vulkan layers data directory.

The zip-archive script was having trouble pulling in data from gen/.
Instead use a separate 'angledata' folder.

BUG=angleproject:1810

Change-Id: I09eaf4766a8360c40af9335bed74a5dc347e05ad
Reviewed-on: https://chromium-review.googlesource.com/435518
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/scripts/generate_vulkan_layers_json.py b/scripts/generate_vulkan_layers_json.py
index 8cbcef2..77990c2 100644
--- a/scripts/generate_vulkan_layers_json.py
+++ b/scripts/generate_vulkan_layers_json.py
@@ -10,7 +10,7 @@
 
 import os, sys, json, glob
 
-if len(sys.argv) < 3:
+if len(sys.argv) != 3:
     print("Usage: " + sys.argv[0] + " <source_dir> <target_dir>")
     sys.exit(1)