Does MT-safe libstdc++ work?

[Andrew Zabolotny]

The subject says it all. I've tried to compile a multithread-safe version
of libc++ (particularily libio)
and 1st) encountered a duplicated definition of 
  static _IO_lock_t _IO_stdfile_##FD##_lock = _IO_lock_initializer; \
in stdstrbuffs.cc, and besides that can't understand how this can work at
all, while, for example:

int
_IO_putc (c, fp)
     int c;
     _IO_FILE *fp;
{
  int result;
  CHECK_FILE (fp, EOF);
  _IO_cleanup_region_start ((void (*) __P ((void *))) _IO_funlockfile,
fp);
  _IO_flockfile (fp);
  result = _IO_putc_unlocked (c, fp);
  _IO_cleanup_region_end (1);
  return result;
}

^^^ If you see, the file is locked with IO_flockfile() and never unlocked.
And there are plenty of other similar places.
What the argument to  _IO_cleanup_region_end () means? Is 1 meaning to
invoke cleanup routine before
removing it from cleanup chain and 0 meaning to not do it?

So, my main two questions are:
a) which macros/functions (and how, i.e. in which includes) should I
override/define to make libstdc++ work multithread-safe under my OS
(OS/2).
b) should I do it at all, if the file functions in libc (i.e. open(),
write() etc) which libio uses *are* thread-safe?

Greetings,
    _\ndy@teamOS/2