apidump: Change gn json file generator filename output

The gn build json file generator script needs to modify the
default VulkanTools json filename format to match what ANGLE
expects, i.e.:
    VkLayer_api_dump.json -> VkLayer_lunarg_api_dump.json

scripts/gn/generate_vulkantools_layers_json.py

@@ -95,9 +95,11 @@ def main():
  if not json_in_name.endswith('.json.in'):
  continue
  json_in_fname = os.path.basename(json_in_name)
- layer_name = json_in_fname[:-len('.json.in')]
+ # VulkanTools repository json.in filenames omit the "_lunarg_"
+ corrected_vt_layer_name = json_in_fname.replace("VkLayer_", "VkLayer_lunarg_")
+ layer_name = corrected_vt_layer_name[:-len('.json.in')]
  layer_lib_name = layer_name + file_type_suffix
- json_out_fname = os.path.join(target_dir, json_in_fname[:-len('.in')])
+ json_out_fname = os.path.join(target_dir, corrected_vt_layer_name[:-len('.in')])
  with open(json_out_fname,'w') as json_out_file, \
  open(json_in_name) as infile:
  for line in infile: