Fix bug https://trac.osgeo.org/grass/ticket/999 (zero divisor)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@41431 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.mfilter/getfilt.c

@@ -85,7 +85,7 @@ FILTER *get_filter(char *name, int *nfilters, char *title)
 		have_divisor = 1;
 		if (sscanf(buf, "DIVISOR %lf", &div) == 1) {
 		    f->divisor = div;
-		    if (n == 0)
+		    if (div == 0)
 			f->dmatrix = f->matrix;
 		    continue;
 		}