libchromeos: Move stream access helper functions to stream_utils.h

Moved IsReadAccess/IsWriteAccess helpers from stream.h to stream_utils
and added MakeAccessMode() helper. Swept the remaining code that used
access mode manipulations to use the helpers.

BUG=None
TEST=`FEATURES=test emerge-link libchromeos`

Change-Id: I0527f8dbda5724ccef14560e064dd607c90197d3
Reviewed-on: https://chromium-review.googlesource.com/269975
Trybot-Ready: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
6 files changed