Enable deprecation warnings on deps of jsoncpp on CrOS

Requires replacing to uses of deprecated codecvt_utf8 with
base/ functions (less code, too).

The base/ functions can't be used with string literals though,
so make a char16_t copy of a test string literal instead of
converting at runtime (see the
bluetooth_notification_controller_unittest.cc change in
https://chromium-review.googlesource.com/c/chromium/src/+/2881379
for reference).

Bug: 983223,1394435,1189439
Change-Id: Icdd9e0a48f848f80c4335031c6492a117da2a04f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4068001
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1078039}
NOKEYCHECK=True
GitOrigin-RevId: a6d8649b6891ee8dd683fa7081ab04be22d86e8c
1 file changed