Fix build with Qt 5.15

Summary:
QPainterPath is no longer included via qtransform.h (since
5.15.0-beta2, 50d2acdc93b4de2ba56eb67787e2bdcb21dd4bea in qtbase.git).

Test Plan: Builds

Reviewers: #calligra:_3.0, danders

Differential Revision: https://phabricator.kde.org/D28403

(cherry picked from commit f77fb06dc5d9f7930da9c757d6916f1149dc42bd)