Remove 'inline' marker on HllFinalEstimate()

HllFinalEstimate() is used outside the file where it's defined, so we
can't mark it inline without angering the linker. This only triggers on
release builds, since inlining is ignored in debug builds.

Change-Id: I966f9dfad17b78a88224ae81f200ed7c5a79921c
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5420
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: Henry Robinson <henry@cloudera.com>