Calling memcpy with either src or dst as nullptr is undefined
even if the count is 0.
Discovered by running tests with -fsanitize=undefined
safe_struct.extension_add_remove specifcially
Adding Tracy in VVL showed that we are paying the price of initializing
global variables upon shared library entry, even if we do not
end up accessing those.
Adding accessors will make sure we pay this price
only when truly needed.
Also making the necessary changes in VVL.
This code was being generated in both Vulkan-ValidationLayers
and Vulkan-ExtensionLayer. Further uses are on the horizon so
lets stop the copypasta.
Also, add functions to manipulate extension lists and pNext chains,
since many client layers have been doing that themselves.
