IMPALA-2992: Clean up scan ranges which are filtered out
IMPALA-2992: Clean up scan ranges which are filtered out

Previously, when a scan range is filtered by the runtime
filter, any queued buffers for that scan range will not be
released, thus leaking IO buffers associated with that scan
range. This change fixes the filtering path by calling
ScanRange::Cancel() for filtered scan ranges so appropriate
clean up will happen.

Change-Id: I5e6f7c6871e0297cc04b04218a7bdaed037a7ac7
Reviewed-on: http://gerrit.cloudera.org:8080/2191
Reviewed-by: Michael Ho <43544f6c6f19372b140301f92a3768afc300868a@cloudera.com>
Tested-by: Internal Jenkins

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