scripts: Prevent bad dynamic array in vk_helper.py
scripts: Prevent bad dynamic array in vk_helper.py

An extension added some variables which defeat the mechanisms
used by the header-parsing scripts to identify dynamic arrays.

Change-Id: Idcf84f882b13bf5cc3be8b6bb48751db6922e01e

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers