cameracalibrate: Fix build error on Mac OSX
It fails to build only on Mac OSX with the following error.
In file included from ../subprojects/gst-plugins-bad/ext/opencv/gstopencv.cpp:45: ../subprojects/gst-plugins-bad/ext/opencv/gstcameracalibrate.h:96:38: error: a space is required between consecutive right angle brackets (use '> >') std::vector<std::vectorcv::Point2f> imagePoints; ^~ > > 1 error generated.
Fix: #817 (closed)