temporary fix for graphic glitches

this force composes the UI elements via the GPU only.

proven to reduce graphic glitches

This should be reverted if necessary when the cause of lack of hardware rendering  is discovered.

Possible side-effects:larger load on the GPU.

Advantages :reduced load on the CPU.

should be coupled with a single entry in egl.cfg to include rendering only via GPU.

hence allowing for a better and smoother UI experience.

PS this is the default behavior in Nexus devices