MINOR: channel/applets: Stop to test CF_WRITE_ERROR flag if CF_SHUTW is enough

In applets, we stop processing when a write error (CF_WRITE_ERROR) or a shutdown
for writes (CF_SHUTW) is detected. However, any write error leads to an
immediate shutdown for writes. Thus, it is enough to only test if CF_SHUTW is
set.
15 files changed