OpenFile portal: do not use O_PATH fds

OpenFile portal: do not use O_PATH fds

Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=03cbcba7b2b0e42a
Last-Update: 2023-05-13

Using O_PATH requires correctly specifying whether the fd is writable or
not. Stating that the fd is writable without it actually being writable
results into rejection on xdg-desktop-portal side. Other implementations
like xdg-open or gtk have also moved away from O_PATH fds so this will
make a matching implementation and avoid possible rejections from xdp.

Gbp-Pq: Name dont_use_O_PATH.diff