openfimg: compiler: Now seriously fix loop emission

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Emit dummy shader if compilation fails

This should at least prevent the hardware from getting stuck.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Prepare for shader linking

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Implement linking of shader semantics

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: compiler: Try to override shader before compilation

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