Coredump-N：fprintf第一个参数为空；同步问题

(gdb) bt
#0 0xf70aea33 in _IO_vfprintf_internal (s=0x0, format=0x8353c98 “%02d-%02d-%04d %02d:%02d:%02d File Opened\n”, ap=0xf31fefa8 “\v”) at vfprintf.c:1311
#1 0xf70b67dc in __fprintf (stream=0x0, format=0x8353c98 “%02d-%02d-%04d %02d:%02d:%02d File Opened\n”) at fprintf.c:32
#2 0x08085c0d in LogFileIO::Open (this=0x84d3b50 ) at /log.cpp:107

只有定义IO_DEBUG的时候，才会做这个null检查。如果没有定义，就不做null的check，就会出现coredump

#ifdef IO_DEBUG
# define CHECK_FILE(FILE