This patch collects the shader storage block members information.
It implements getShaderStorageBlockMemberInfo and getShaderStorageBlockSize
for OpenGL backend. Meanwhile, it implements BUFFER_VARIABLE and SHADER_STORAGE_BLOCK
interfaces for program query.

BUG=angleproject:1920
TEST=angle_end2end_tests:ProgramInterfaceTest*
     dEQP-GLES31.functional.layout_binding.ssbo*
     dEQP-GLES31.functional.compute.basic.empty
     dEQP-GLES31.functional.compute.basic.ssbo_rw*
     dEQP-GLES31.functional.compute.basic.ssbo_local_barrier*
     dEQP-GLES31.functional.compute.basic.copy_image_to_ssbo_small
     dEQP-GLES31.functional.compute.basic.copy_ssbo_multiple_groups
     dEQP-GLES31.functional.compute.basic.copy_ssbo_multiple_invocations
     dEQP-GLES31.functional.compute.basic.copy_ssbo_single_invocation
     dEQP-GLES31.functional.compute.basic.copy_ssbo_to_image_small
     dEQP-GLES31.functional.compute.basic.shared_var*
     dEQP-GLES31.functional.compute.basic.ubo_to_ssbo*
     dEQP-GLES31.functional.compute.basic.write_multiple_arr*
     dEQP-GLES31.functional.compute.shared_var.basic_type.*
     dEQP-GLES31.functional.compute.shared_var.work_group_size.*
     dEQP-GLES31.functional.atomic_counter.*

Change-Id: Ie8b81fde5a2e919aab77adb3d137c9ff2f193409
Reviewed-on: https://chromium-review.googlesource.com/712235Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>