radeonsi: send shader info as debug messages in addition to stderr output

radeonsi: send shader info as debug messages in addition to stderr output

The output via stderr is very helpful for ad-hoc debugging tasks, so that remains
unchanged, but having the information available via debug messages as well
will allow the use of parallel shader-db runs.

Shader stats are always provided (if the context is a debug context, that is),
but you still have to enable the appropriate R600_DEBUG flags to get
disassembly (since it is rather spammy and is only generated by LLVM when we
explicitly ask for it).

Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>