include `opencv2/video/tracking.hpp`

[TooTallNate]

I was getting this error when trying to build on Alpine Linux:

‘calcOpticalFlowPyrLK’ is not a member of ‘cv’

Including tracking.hpp fixes compilation for me.

Related: https://stackoverflow.com/a/11641833/376773

[codecov-io]

Codecov Report

Merging #550 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #550   +/-   ##
=======================================
  Coverage   51.19%   51.19%           
=======================================
  Files          34       34           
  Lines        3899     3899           
  Branches       27       27           
=======================================
  Hits         1996     1996           
  Misses       1903     1903

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 52333d4...49b9f42. Read the comment docs.