Revert "Optimize syslog_write performance"

[fjpanag]

Reverts #6618

PR #6618 broke syslog, and it must be reverted (at least temporarily).

The buffer passed to syslog_default_write() is NOT NULL-terminated.
Printing depends on the value of buflen.

On the other hand, up_puts() needs the string to be NULL-terminated.

As a result, syslog over-runs the buffer and prints garbage.

The offending commit is specifically 8254ad9.

[xiaoxiang781216]

@fjpanag the new approach call up_nputs not up_puts, so it isn't a problem that the buffer isn't terminated by null pointer. Could you point out more specific place which assume the buffer is null terminated?

[fjpanag]

@xiaoxiang781216 in file syslog_channel.c in function syslog_default_write() there is a call to up_puts().

[pkarashchenko]

@fjpanag maybe better to replace that single call of up_puts() in syslog_default_write() with up_nputs() instead of reverting?

[xiaoxiang781216]

@pkarashchenko @fjpanag please review patch #6661

[fjpanag]

Closing in favor of #6661.