Revert "snapuserd: opt out of Global ThinLTO to workaround segfault"

This reverts commit 9d0c06d3.

The failure is fixed by https://r.android.com/2725997. Workaround no
longer needed.

Test: manual
Bug: 208565717
Bug: 295944813
Change-Id: I83638938bf52a4b2b1e72743f892c579622ba9e6