Add tests with multiple color attachments without export
These new tests are to verify if it works correctly when some of color
attachments are not exported in FS.
This also includes a tiny refactor to reuse testDifferentAttachmentSizes
since it's using multiple render targets in FS.
- testDifferentAttachmentSizes -> testMultiAttachments
- makeRenderPassDifferentAttachmentSizes -> makeRenderPassMultiAttachments
New tests:
dEQP-VK.pipeline.*.framebuffer_attachment.multi_attachments_not_exported*
Affects:
dEQP-VK.pipeline.*.framebuffer_attachment.*
VK-GL-CTS Issue: 3927
Components: Vulkan
Change-Id: I863e29c7c7640ee024fc098c31e41fcddf6086c0