KUDU-1171: Correctly increment completed scan ranges
KUDU-1171: Correctly increment completed scan ranges

Impala uses the completed scan ranges counter for internal bookkeeping
and presenting the end user some kind of progress. This patch correctly
initializes and increments the counter for Kudu scans.

Change-Id: I996dbfde33a669160ad7a5c2475b106062208610
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/8296
Reviewed-by: David Alves <33ea948168c114d220e0372a903be6ee60f6396e@cloudera.com>
Tested-by: jenkins

michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala