Revert "Using Qt5Core rather than Qt5Widget for the version check"

Authored by lbeltrame on Sep 6 2018, 7:51 AM.

Description

Revert "Using Qt5Core rather than Qt5Widget for the version check"

Build system changes can be potentially breaking and so must be reviewed
prior to commit. In addition, there is no explanation for this change.

Simon, you might want to submit your patches to Phabricator for review
prior to landing them.

CCMAIL: sdepiets@gmail.com

This reverts commit 831db7ed507a33f859901dae7274115be22fcc1a.