* let iris handle buffer management, this implies that BOs are mapped to
the PPGTT during buffer execution and unmapped by iris later, for this
to work buffers need to be unmapped when allocating cached BOs
(vma_free) which requires a patch
* support lseek (drm_lseek for now) for determining object size
issue #4380
* Switch mesa support from DRI to gallium
Supported drivers are
- softpipe (Sebstian Sumpf)
- iris for Intel GPUs (Alexander Boetcher)
- etnaviv for Vivante GPUs (Josef Söntgen)
* Mesa's generated files are placed into 'contrib/mesa-<hash>/generated'
and are cloned per default from a separate Git repo in order to avoid
hash updates upon package build. In case you need to generate files
yourself use
! prepare_port mesa GENERATE_FILES=1
issue #4254
