Support an env var to generate SDL checkpoints for a HAC

contrib/sdl_checkpoints.pl

@@ -8,7 +8,11 @@
 
 use warnings;
 use strict;
-my $hush    = "./src/hush-cli";
+
+# call this script like this to generate checkpoints for a HAC such as DragonX:
+# CLI=./src/dragonx-cli ./contrib/sdl_checkpoints.pl ...
+
+my $hush    = $ENV{CLI} || "./src/hush-cli";
 my $gethash = "$hush getblockhash";
 my $gettree = "$hush getblockmerkletree";
 my $start   = shift || 300000;