Update FBO completeness checks for depth textures Trac #20875 Signed-off-by: Nicolas Capens - improve missing attachment logic to allow no color attachments - disallow depth texture color attachments - allow texture depth and stencil attachments - update simulaneous depth/stencil logic git-svn-id: https://angleproject.googlecode.com/svn/trunk@1113 736b8ea6-26fd-11df-bfd4-992fa37f6226