缓冲输出模式的bug

[mojinpan]

elog_buf_output()函数有问题，输出不完整
`void elog_buf_output(const char *log, size_t size) {
size_t write_size = 0, write_index = 0;

if (!is_enabled) {
    elog_port_output(log, size);
    return;
}

//循环有什么用？每次调用此处只会被执行一次
while (true) {
if (buf_write_size + size > ELOG_BUF_OUTPUT_BUF_SIZE) {
//缓冲区满时log被拆分输出？
write_size = ELOG_BUF_OUTPUT_BUF_SIZE - buf_write_size;
memcpy(log_buf + buf_write_size, log + write_index, write_size);
//write_index不是静态局部变量，此处有意义？
write_index += write_size;
size -= write_size;
buf_write_size += write_size;
/* output log /
elog_port_output(log_buf, buf_write_size);
/ reset write index */
buf_write_size = 0;
} else {
memcpy(log_buf + buf_write_size, log + write_index, size);
buf_write_size += size;
break;
}
}
}`

修改成以下代码后测试正常：
`void elog_buf_output(const char *log, size_t size)
{
//未使能缓冲输出时直接输出
if (!is_enabled) {
elog_port_output(log, size);
return;
}
//缓冲区空间不足时先输出
if (buf_write_size + size > ELOG_BUF_OUTPUT_BUF_SIZE) {
elog_port_output(log_buf, buf_write_size);
buf_write_size = 0;
}
//日志拷贝至缓冲区
memcpy(log_buf + buf_write_size, log, size);
buf_write_size += size;

}`

[armink]

buf 缓冲模式，基本没有被应用，有问题欢迎提交 pr