build: add missing OpenCV lib dependency

Signed-off-by: deadprogram <[email protected]>

.travis.yml

@@ -52,7 +52,7 @@ before_script:
    - sh -e /etc/init.d/xvfb start
 script:
    - export CGO_CPPFLAGS="-I${HOME}/usr/include"
-   - export CGO_LDFLAGS="-L${HOME}/usr/lib -lopencv_core -lopencv_videoio -lopencv_imgproc -lopencv_highgui -lopencv_imgcodecs -lopencv_objdetect -lopencv_calib3d"
+   - export CGO_LDFLAGS="-L${HOME}/usr/lib -lopencv_core -lopencv_videoio -lopencv_imgproc -lopencv_highgui -lopencv_imgcodecs -lopencv_objdetect -lopencv_calib3d -lopencv_video"
    - echo "Ensuring code is well formatted"; ! gofmt -s -d . | read
    - bash -c 'set -e; echo "" > coverage.txt; for d in $(go list ./...); do go test -covermode=set -coverprofile=p.out $d; if [ -f p.out ]; then cat p.out >> coverage.txt; rm p.out; fi; done'
 after_success: