Implement support for mipmap generation (CopyTexImage2D regression)
Implement support for mipmap generation (CopyTexImage2D regression)

TRAC #11338

CopyTex(Sub)Image2D was broken by the coordinate space change. Render targets are rendered flipped in the Y axis.

Signed-off-by: Nicolas Capens
Signed-off-by: Daniel Koch

Author:    Andrew Lewycky

csulmone/angle,csulmone/angle,csulmone/angle,csulmone/angle