openfimg: Use a helper to add buffers to batches

This simplifies debugging and facilitates adding assertions on buffers.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: Handle buffer referencing properly

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Handle quirks of hardware TEXKILL instruction

The hardware implements it the D3D way, which makes it check only x, y
and z channels, while the TGSI instruction is defined to check all four.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Fix incorrect assumption in interference removal

The function might be called even for variables that have not been
marked as interfering or do not interfere with any other variables at
all.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>