Naive concatenation of $LD_LIBRARY_PATH can result in an empty
colon-delimited segment; this tells glibc to load libraries from the
current directory, which is definitely wrong, and may be a security
vulnerability if the current directory is untrusted. (See #67234, for
example.) Fix this throughout the tree.
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
This switches a majority of the applications to using qt5.mkDerivation
which automatically adds wrapQtAppsHook.
In certain places, where GLib and gtk intersect with Qt, we
also needed to use wrapGAppsHook. In these cases there will
be multiple wrappers.
