Generalize GetUniformBlockInfo. This method is useful for the Vulkan back-end as well as D3D11. It can produce a uniform block layout for the default uniform blocks as well as for interface blocks. Put it in blocklayout.h in the translator. BUG=angleproject:2167 Change-Id: I13160906921da439746c1811a623006250aaeefd Reviewed-on: https://chromium-review.googlesource.com/713941 Reviewed-by: Frank Henigman <fjhenigman@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>