dvgrab wait for device

if there is no device when dvgrab is first run, it aborts.  Yet if it
is streaming I can unplug the device and plug it back in, and the
stream continues.  If there were some way to get dvgrab to just wait
for a device, that would be great.  Or if someone can replace the
execvp(dvgrab with the C code from dvgrab... then I can take that off
my list of things to look into :)

-- 
Carl K

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