Ignore asterix-opt

This change adds asterix-opt to gitignore in order to not push
extension development code into the apache asterixdb repository

Change-Id: I5199c8c0d166ef5e5ed70b541e0b96e485801d68
Reviewed-on: https://asterix-gerrit.ics.uci.edu/903
Reviewed-by: Till Westmann <tillw@apache.org>
Reviewed-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
diff --git a/.gitignore b/.gitignore
index ced139e..636fb2f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@
 asterix_logs
 build
 bin
+asterixdb/asterix-opt/
 asterixdb/asterix-app/src/test/resources/externallib/
 asterixdb/asterix-app/rttest/
 asterixdb/asterix-app/mdtest/