Bug#779608: xvfb: cleanup on signal exits as well

[Jérémy Lal <jerry@eda.sarl>]

Hello Ximin,

i tried your patch, and now when interrupting using ctrl-c

xvfb-run -a myapp

i get (i added the "cleaning" message):

^Ccleaning /tmp/xvfb-run.UlOS0T

cleaning /tmp/xvfb-run.UlOS0T

rm: cannot remove '/tmp/xvfb-run.UlOS0T': No such file or directory

xvfb-run: error: problem while cleaning up temporary directory

obviously cleanup is run twice.

Jérémy