Fix a leak of fallback dialog helper in xdgdesktopportal
requested to merge asturmlechner/qtbase:QTBUG-98988-xdgdesktopportal-leak-of-fallback-helper into kde/5.15
Task-number: QTBUG-98988 Pick-to: 6.4 6.3 6.2 5.15 Change-Id: Id066f0dd2cacbc273deacd4f7df66c3787ad4017 Reviewed-by: Thiago Macieira thiago.macieira@intel.com (cherry picked from commit 36c1a7ba)