aco: set constant_data_offset correctly in the case of merged shaders
setup_nir() is done for all shaders before any of them are selected, so constant_data_offset could be incorrect for the first shader. Fixes incorrect geometry in Mafia III and Max Payne 3. Signed-off-by:Rhys Perry <pendingchaos02@gmail.com> Reviewed-by:
Samuel Pitoiset <samuel.pitoiset@gmail.com> Cc: mesa-stable Closes: mesa/mesa#2768 Part-of: <mesa/mesa!6205>