Bunch of bit flag constants are set to None

[jsfrancal]

Hi,

Thanks for excellent wrapper! I am using some dynamic binding extensions and I'm noticing that they're set to None in the _vulkan.py file, possibly due to automatic generation error:

DESCRIPTOR_POOL_CREATE_UPDATE_AFTER_BIND_BIT_EXT = None
VK_DESCRIPTOR_SET_LAYOUT_CREATE_UPDATE_AFTER_BIND_POOL_BIT_EXT = None

Both of these are supposed to be 2 for example (which is the temporary workaround) And there's a whole lot of other bit constants that are set to None there and probably shouldn't be. Thanks.