The XIM test carried its own Xvfb and daemon spawner, its own child
struct, log files and process-group teardown, and the GTK test a second
Xvfb launcher, because live.c's startdaemon always unset DISPLAY. Live
now carries the display its own startxvfb reports, startdaemon passes it
on, and both tests use the shared pair: 300 lines fewer, one place that
knows how a child is started, watched, and stopped.