etnaviv: add etna_ringbuffer_emit(..)

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
etnaviv: test: generate cmd stream

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
etnaviv: test: add quick 'n dirty bitmap dumper

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
etnaviv: test: dump bo for visual inspection

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Merge branch 'master' of github.com:austriancoder/libdrm