kms: New backend

New backend utilizing a thread per surface for precise frame
scheduling.

src/backend/render/element.rs

@@ -8,7 +8,7 @@ use smithay::{
             utils::{CropRenderElement, Relocate, RelocateRenderElement, RescaleRenderElement},
             Element, Id, Kind, RenderElement, UnderlyingStorage,
         },
-        gles::GlesTexture,
+        gles::{GlesError, GlesTexture},
         glow::{GlowFrame, GlowRenderer},
         utils::{CommitCounter, DamageSet, OpaqueRegions},
         Frame, ImportAll, ImportMem, Renderer,
@@ -465,3 +465,13 @@ impl<R: Renderer> RenderElement<R> for DamageElement {
         Ok(())
     }
 }
+
+pub trait FromGlesError {
+    fn from_gles_error(err: GlesError) -> Self;
+}
+
+impl FromGlesError for GlesError {
+    fn from_gles_error(err: GlesError) -> Self {
+        err
+    }
+}