Blender Git Loki

Fix T53512: Vertices with index 0 were not being selected

Bug introduced on rB9f5bf197a0c3.
The offset for selection of vertices (`bm_vertoffs`) starts where the offset o edges ends (`bm_wireoffs`).
However, the `bm_wireoffs` depends on the offset of face selection (`bm_solidoffs`).

Before the commit that introduced the bug, the drawn of edges (in backbuff) was always computed along with the `bm_wireoffs`:
```
bm_wireoffs = bm_solidoffs + em->bm->totedge;
```

Now that the edges are not always drawn in backbuff, `bm_wireoffs` has to start from `bm_solidoffs`.