Fix custom builds with indexeddb enabled

Our build-system needs a few updates to make indexeddb enablable again.

This patch does not provide any API for indexeddb or enable indexeddb
itself. It only updates the build system for default disabled feature.

Change-Id: I1ca61bda0913f698bbdf716d286a50051dbe1a99
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>