r.viewshed: more informative error message if maxDimension (rows/cols) is exceeded

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@60858 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.viewshed/grass.cpp

@@ -108,8 +108,11 @@ GridHeader *read_header(char *rastName, Cell_head * region)
 	hd->nrows = (dimensionType) nrows;
 	hd->ncols = (dimensionType) ncols;
     }
-    else
+    else {
+	G_warning("ERROR: nrows (%d) > maxDimension (%d) AND/OR ncols (%d) > maxDimension (%d)", 
+	           nrows, maxDimension, ncols, maxDimension);
 	G_fatal_error(_("Grid dimension too big for current precision"));
+    }
 
 
     /*fill in rest of header */