misc/qtchooser provides a wrapper binary bin/qtchooser, that when called with
name foo, will lauch the corresponding binary from
Previously qtchooser would install a list of 30-ish symlinks to itself automatically.
Now we switch this around.
qt-dist ports that define QT_BINARIES will now have a @postexec and @postunexec
entry added to their plist to run the shell-script update-qtchooser-wrapper
(installed by qtchooser).
update-qtchooser-wrapper removes all symlinks to bin/qtchooser that have no
corresponding binary in lib/qt*/bin, and readds links that are missing.