depends: Prune X packages
Summary:
We noticed that we could build QT without using XLib/libX11 as a library. XLib/libX11's headers are still used, and a minimal configure.ac has been added to eliminate overly-enthusiastic configure-time dependencies that aren't actually required to obtain the headers. This also means that we eliminate XLib/libX11 as required shared libraries at runtime, which is desirable.
Backport of core PR16408.
Depends on D5632.
Test Plan: Run the Gitian builds.
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D5636