Merge branch 'mobica_fix_spirv_validation_errors' into 'vulkan-cts-1.0-dev'

Merge branch 'mobica_fix_spirv_validation_errors' into 'vulkan-cts-1.0-dev'

Explicitly declare gl_PerVertex block

This fixes SPIR-V validation error in shaders generated from GLSL (not ES) due to missing ClipDistance capability.

I'm adding "for discussion" label to highlight this. Also not sure if we really need to make these fixes, or should this be dealt with someplace else.

Affected tests (at least those I noticed):

- dEQP-VK.draw
- dEQP-VK.binding_model
- dEQP-VK.pipeline.early_fragment
- dEQP-VK.pipeline.spec_constant

See merge request !590