Bug#1112007: autopkgtest depends on r-cran-gstat which is not in testing

[Rebecca N. Palmer]

Control: block -1 by 1102537

r-cran-gstat is not in testing because it has never worked on s390x 
(#1102537).  The planned solution is to remove it on that architecture, 
but this may take some time because of the large dependency tree to be 
removed with it.