[ASTERIXDB-2461][FUN] Fix LocalAvgTypeComputer

- user model changes: yes
- storage format changes: no
- interface changes: no

Details:
1. Changed the type of count from INT32 to INT64 because AVG uses a long
to store count

commit 7cfdaf0b8fb452ead4183a8f24a5b5dd21354fa0
Author: James Fang <jfang003@ucr.edu>

Change-Id: Ic693d027190b43fa3deaaf83ebf73f62c77d5a76
Reviewed-on: https://asterix-gerrit.ics.uci.edu/2996
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Dmitry Lychagin <dmitry.lychagin@couchbase.com>
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/LocalAvgTypeComputer.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/LocalAvgTypeComputer.java
index a5858d7..f9ffa86 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/LocalAvgTypeComputer.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/typecomputer/impl/LocalAvgTypeComputer.java
@@ -38,7 +38,7 @@
             IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
         return new ARecordType(null,
                 new String[] { "sum", "count" }, new IAType[] {
-                        AUnionType.createNullableType(BuiltinType.ADOUBLE, "OptionalDouble"), BuiltinType.AINT32 },
+                        AUnionType.createNullableType(BuiltinType.ADOUBLE, "OptionalDouble"), BuiltinType.AINT64 },
                 false);
     }
 }