lib: Double check ring measurement

Check twice for the signal interrupting the execbuf, because the real
world is messy.

References: https://bugs.freedesktop.org/show_bug.cgi?id=106695
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Antonio Argenziano <antonio.argenziano@intel.com>
Reviewed-by: Antonio Argenziano <antonio.argenziano@intel.com>
1 file changed