Uniforms and varyings structures were simply validating
that both versions in fragment and vertex shaders were
structures, without validating that the fields actually
matched.

All the structures and data required to perform the
validation at link time was added.

Fixes:
dEQP-GLES3.functional.shaders.linkage.uniform.struct.type_conflict_1

Change-Id: Icbf888bbebf4ccf7d27f48cb98d4cd7ea5b42ca3
Reviewed-on: https://swiftshader-review.googlesource.com/15848Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>