*: Use fprintf between qemu_log_trylock/unlock

Inside qemu_log, we perform qemu_log_trylock/unlock, which need
not be done if we have already performed the lock beforehand.

Always check the result of qemu_log_trylock -- only checking
qemu_loglevel_mask races with the acquisition of the lock on
the logfile.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220417183019.755276-10-richard.henderson@linaro.org>