Blender Git Loki

Fix viewport rendering with anti-aliasing - workaround

This commit makes the fullsample option for viewport renderings always
on: Render > OpenGL Render Options > Full Sample.

(The UI still allows users to set this, so we will need to revisit this
before 2.8 releases).

Even in computers that can handle MSAA we had issues.
The way Blender gpu_* implementation is handling anti-aliasing is buggy.
For example, in Blender 2.7x if you have depth of field in a viewport
with multi-sampling, the DoF gives us jagged edges.

Since Eevee uses framebuffers for a lot of things, this issue was
leading to very visible buggy render in some computers, and more subtle
inconsistent buggy renders in others (easy to test with the depth of
field in Eevee).