Bug#944341: libopencv-imgcodecs-dev depends on cruft package.

[peter green]

package: libopencv-imgcodecs-dev
version: 4.1.2+dfsg-4
severity: serious

The libopencv-imgcodecs-dev binary package depends on and the opencv source 
package build-depends on libgdcm2-dev which is no longer built by the gdcm 
source package.