Use non-deprecated KDEInstallDirs variables in cross-compiling cmake code
No clue about that cross-compiling thing. But I would assume that BIN_INSTALL_DIR is still taken from KDEInstallDirs, where it is part of the deprecated set of variables (due to not being namespace-prefixed), which after all the years should be finally phased out in time for KF6 :)
@vkrause @apol @cullmann (those involved in https://phabricator.kde.org/D25143 )