opengl: Correct transformation order in GLTexture::render()
First, the texture-to-buffer transform has to be applied, then the y axis should be flipped. Doing it vice versa changes the winding order of rotation transforms.
Also the screenshot plugin uses incorrect render transform. Since convertFromGLImage() undoes the render target's transform, the color space transformation pass should use the same transform, not the inverted one.
(cherry picked from commit f23e0ef0)