Fix bugs preventing Pixmap re-use

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@39866 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/cairodriver/Graph.c

@@ -185,7 +185,7 @@ static void init_file(void)
 #if CAIRO_HAS_XLIB_XRENDER_SURFACE
     if (is_xlib) {
 	if (do_read)
-	    cairo_read_image();
+	    cairo_read_xid();
 	else
 	    ca.win = 0;
 	init_xlib();

lib/cairodriver/read_xid.c

@@ -16,7 +16,7 @@ void cairo_read_xid(void)
     if (!fgets(buf, sizeof(buf), fp))
 	G_fatal_error(_("Unable to read input file <%s>"), ca.file_name);
 
-    if (sscanf(buf, "%lu", &xid) != 1)
+    if (sscanf(buf, "%lx", &xid) != 1)
 	G_fatal_error(_("Unable to parse input file <%s>"), ca.file_name);
 
     fclose(fp);