lxapigen.sh: Report diffs of new files instead of a weird error.

lxapigen.pl

@@ -248,7 +248,7 @@ EOF
 
     close(OUT);
 
-    if ((system("diff -u '$finalfname' '$outfname'") == -1) || ($? != 0)) {
+    if ((system("diff -uN '$finalfname' '$outfname'") == -1) || ($? != 0)) {
         rename($outfname, $finalfname) or die("Failed to rename '$outfname' to '$finalfname': $!\n");
     } else {
         unlink($outfname);  # they match, just delete the new copy so build system doesn't rebuild everything.