[Piglit] [PATCHv2 0/5] arb-enhanced-layouts: explicit-offset piglits

[Emil Velikov]

Hi all,

Some update over the previous round
 - Add the missing S in enhanced-layouts :)
 - The uniform tests are prefixed with UBO.
 - SSBO tests are added in the respective hunks.
 - The final (negative link) test has been added.

Note: all of these are written based on the spec alone and haven't been 
verified against existing OpenGL implementations (the official NVIDIA 
driver does not play well on my ageing laptop).

Please review, bikeshed and/or flame away.

Thanks,
Emil