message: Fix NVPTX TargetMachine construction to use reloc/code model flags only if explicitly set. Fixes failures caused by r348585.
diff: @@ -199,8 +199,7 @@ std::unique_ptr<llvm::TargetMachine> GetTargetMachine(
  }
  return absl::WrapUnique(target->createTargetMachine(
  triple.str(), llvm_ir::AsStringRef(cpu_name), "+ptx60", target_options,
  - Optional<Reloc::Model>(RelocModel), Optional<CodeModel::Model>(CMModel),
  - codegen_opt_level));
  + getRelocModel(), getCodeModel(), codegen_opt_level));
  }
  // Adds the standard LLVM optimization passes, based on the speed optimization
  