Wire up -fpie and -fPIE to LLVM's newly added TargetOptions. No test

case as we don't currently have any way of dumping target options or
otherwise observing this. Another small step toward fixing PR12380. With
this we generate TLS accesses using the static model instead of the
dynamic model, but we're still generating suboptimal code under the
mistaken assumption that the TLS offset might be greater than 2^32, and
therefor not viable as an immediate offset of a segment register.

llvm-svn: 154298