The otsuThreshold function was creating an empty Array for the sigmas variable
and this sometimes failed because the last value was not always written to. This
commit adjusts the size of the sigmas array to better match the values that are
assigned to it

Prior to this change, edge tracking CPU backend kernel wasn't processing
the batch input sets. Thus, the output of corresponding input sets was
missing in the array returned by canny API. This is fixed now.
Added a batch test for this scenario.

9prady9 deleted the canny_empty_arry_fix branch