gnu: Qt: Update to 5.14.2.

gnu: Qt: Update to 5.14.2.

* gnu/packages/qt.scm (qtsvg, qtimageformats, qtx11extras,
qtxmlpatterns, qtconnectivity, qtwebsockets, qtsensors,
qtmultimedia, qtserialport, qtserialbus, qtwebchannel,
qtwebview, qtlocation, qttools, qtscript, qtquickcontrols,
qtquickcontrols2, qtgraphicaleffects, qtgamepad, qtscxml,
qtpurchasing, qtcharts, qtdatavis3d, qtnetworkauth,
qtspeech, qtwebengine): Update to 5.14.2.
(qtcanvas3d): Remove variable.  Upstream deprecated it.
(qtbase)[source](patches): Remove qtbase-QTBUG-81715.patch.
[arguments]: Drop X11lib substitution: patched dir no longer exists.
(qtwayland)[arguments]: Disable two tests, and add phase to prevent fatal DBus
warnings.
(qtwebglplugin)[inputs]: Add ZLIB.
(qtremoteobjects): Disable some tests that fail due to missing network.
(qtdeclarative)[native-inputs]: Add VULKAN-HEADERS.
(qtwebengine)[source](snippet): Adjust list of preserved files.
[inputs]: Add VULKAN-HEADERS.
* gnu/packages/patches/qtbase-QTBUG-81715.patch: Delete file.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.

Co-authored-by: Marius Bakke <mbakke@fastmail.com>