LD_LIBRARY_PATH leaks to appstreamcli

[wez]

When running on Fedora and including appstream metadata, the linuxdeploy appimage (indirectly?) attempts to run appstreamcli with the environment set to resolve glib from inside the appimage. However, since it is running a binary installed by the host system, the LD_LIBRARY_PATH causes runtime linker errors for the glib symbols referenced by appstreamcli.

I've worked around this in https://github.com/wez/wezterm/commit/90de55f807e596af620b50c48a7f9de54a2aa940 by deploying a little appstreamcli wrapper script early in the PATH to clean its environment.

It would be great to resolve this correctly; I'd suggest either making sure that the plugin cleans the environment first, or alternatively, by bundling the needed utilities in the linuxdeploy appimage and running them from there.