Split the target to allow faster builds for each run.

The overall build time will be more, yet Travis runs multiple builds in
parallel so we're limited by the slowest one.

Things are split roughly as:
 - DRI loaders, classic DRI drivers, classic OSMesa, make check
 - All Gallium drivers (minus the SWR) alongside st/dri (mesa)
 - The Vulkan drivers - ANV and RADV, make check (anv)

v2:
 - rework RUN_CHECK to MAKE_CHECK_COMMAND
 - explicitly disable DRI loaders
 - generate linux/memfd.h locally and enable ANV
 - add libedit-dev

v3: Use printf to create the header (Andres).
v4: Really add the libedit + printf hunks.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Andres Gomez <agomez@igalia.com>