When an interface block's field is determined to be active, it's
possible that the field is a struct so each of that field's fields need
to be marked active as well.

Bug: angleproject:3596
Test: dEQP-GLES31.functional.program_interface_query.*
Test: end2end ProgramInterfaceTestES31
Change-Id: I0bf550046a7a1d3c92cc08773138a40400e5e73b
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1749332Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Tim Van Patten <timvp@google.com>