clover/llvm: Drop dead code.

clover/llvm: Drop dead code.

This ifdef'ed out code was meant to handle compilation into TGSI, but
it doesn't seem likely that it will ever be useful even if the TGSI
back-end is resurrected because the TGSI bitcode can just be plumbed
through in ELF format and dealt with as a regular "native" back-end.

Reviewed-by: Serge Martin <edb+mesa@sigluy.net>
Tested-by: Jan Vesely <jan.vesely@rutgers.edu>