Bug fix: reset io_last_written on c->buf resize to prevent stale
pointers.
Fixes an assert crash in _writeToClient():
serverAssert(c->io_last_written.data_len == 0 ||
c->io_last_written.buf == c->buf);
The issue occurs when clientsCronResizeOutputBuffer() grows or
reallocates c->buf while io_last_written still points to the old buffer
and data_len is non-zero. On the next write, both conditions in the
assertion become false.
Reset io_last_written when resizing the output buffer to prevent stale
pointers and keep state consistent.
PR: 290758
Reported by: chris@cretaforce.gr
9e4efe5e51