The maximum number of mipmap levels supported for cubemap can be determined from the maximum 2D texture size. There is no need to limit the max to 12.
This fixes a regression in creating GL4.1 and up context since commit 2658d025 is now explicitly checking for MaxCubeTextureLevels >= 15 for GL4.1 context.
Reviewed-by: Neha Bhende bhenden@vmware.com
/cc @bhenden