depends: expat 2.2.6 and qt 5.9.7
Summary:
This PR upgrades expat and qt in depends. [...] (commit id) disables a bunch of qt features we aren't currently using. This speeds up the qt depends build slightly (also decreases the size of the built qt-5.9.7 tar by about 2%).
Backport of core PR14849.
Test Plan: Run the Gitian builds.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D5606