fuchsia: Re-enable logging
fuchsia: Re-enable logging

In
https://chromium-review.googlesource.com/c/chromium/mini_chromium/+/2424890
logging on Fuchsia was lost. Previously we always logged via fprintf,
but that got lost as LOG_TO_SYSTEM_DEBUG_LOG was never implemented for
Fuchsia. Follow the POSIX setting since stderr is equally useful until
we have better implementation of logging to the system log.

Bug: fuchsia:74897
Fixed: fuchsia:76641
Change-Id: Ibdf61694d4e8eb724fb4aba2d1c8b13d29aabd2b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/mini_chromium/+/2892939
Reviewed-by: Joshua Peraza <f5809a5e35ec7e1bd0e25cb0a0b68bb433cf6f17@chromium.org>

chromium/mini_chromium,chromium/mini_chromium,chromium/mini_chromium