hg: jdk/sandbox: 8242485: Null _file checking in fileStream::flush()

[chris.hegarty at oracle.com]

Changeset: fd90d09a566e
Author:    ddong
Date:      2020-04-14 16:37 +0800
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/fd90d09a566e

8242485: Null _file checking in fileStream::flush()
Reviewed-by: dholmes, ysuenaga, iklam

! src/hotspot/share/utilities/ostream.cpp
! src/hotspot/share/utilities/ostream.hpp