mesa: release references to image textures when a context is destroyed
When a texture is still bound as an image and the context it was bound in is destroyed but not the texture, then the texture will still hold the resource and will not be freed when it is finally destroyed. Hence, release these references when the context is destroyed.
This leak was triggered by virglrenderer: virgl/virglrenderer#86 (closed)
Signed-off-by: Gert Wollny gert.wollny@collabora.com