Do NOT fall back to ogles2vk_LookupProcAddr()

[afxgroup]

That returns APICALL trampolines (libcall ABI: Self in r3, args in r4-r10) which are only valid when invoked via the AmigaOS interface dispatch. vkGetDeviceProcAddr() is supposed to hand back raw, standard-Vulkan-ABI function pointers that the application calls directly as PFN_vkXxx — feeding a libcall trampoline through that path makes every argument slide by one register slot at call time, which manifests as pCreateInfo/pSwapchain arriving as NULL in downstream functions like ogles2vk_CreateSwapchainKHR.
Match software_vk's behaviour: return NULL for unknown names. The caller can then fall back to its own dispatch (e.g. through IVulkan with proper Self setup) for functions not represented in the RAW table — most notably the WSI swapchain entry points.

Added makefile for cross compilation when not using docker