lavapipe: use C code for extensions + fix zink instance version
While porting to this, it exposes 1.0 vulkan instance api version, however zink wasn't ready for this. This contains some prelim zink fixes for #4371 (closed)
This is the lavapipe port of the extensions in C code from radv/anv.
It drops support for EXT_external_memory_dma_buf which was on by mistake.