create missing directory (for i.class etc.) (trac https://trac.osgeo.org/grass/ticket/70)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@31440 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/imagery/sigfile.c

@@ -9,6 +9,10 @@ FILE *I_fopen_signature_file_new (
     char element[GNAME_MAX*2];
     FILE *fd;
 
+    /* create sigset directory */
+    sprintf(element, "%s/subgroup/%s/sig", group, subgroup);
+    G__make_mapset_element_misc("group", element);
+
     sprintf (element, "subgroup/%s/sig/%s", subgroup, name);
 
     fd = G_fopen_new_misc ("group", element, group);