Check executables exist in PATH before passing them to QProcess
See: https://kde.org/info/security/advisory-20220131-1.txt https://mail.kde.org/pipermail/kde-devel/2022-January/000943.html
Drive-by-change: remove a redundant #include
See: https://kde.org/info/security/advisory-20220131-1.txt https://mail.kde.org/pipermail/kde-devel/2022-January/000943.html
Drive-by-change: remove a redundant #include