Or any Qt5 app will complain:
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
Let's recommended them. On Wayland-based DEs we can export
QT_QPA_PLATFORM=wayland to avoid depending on xcb though.
It looks like we've forgotten some dependencies for Qt5 all the time.
And many dependencies of Qt5 are also needed by the alternative. I
gathered them via
readelf -d $(find -name \*.so) | grep NEEDED | grep -o '\[.*\]' |
sort | uniq | grep -v Qt 2>/dev/null
in the Qt5 alternative build directory.
In the regex we use `|` which is extended regex. So the `-r` (or `-E`,
or `--regexp-exteneded`) option is needed. We cannot squash them into
`-ir` because `-i[PREFIX]` has a special meaning: make a backup named
`tempconf[PREIX]`.
