Blender Git Loki

Edit Mode: Fix element selection on some old AMD GPUs

Tested on an `AMD Radeon HD 7570M`.
It seems that a VBO containing only `unsigned bytes` or `unsigned shorts` can't be read correctly in a shader.
Strange that if the index buffer repeats the drawing of the vertices (as was done before rBa04dd15193e6) the problem disappears.
The disadvantage of this solution is that the memory size for a selection VBO increases by about 4 times.
But the loss in optimization is negligible.


Thanks to @fclem for pointing out the possible source of the problem and reviewing the fix.