PATCH (libstdc++-v3): Address non-portability comment on recent submission

[Loren James Rittle <rittle at latour dot rsch dot comm dot mot dot com>]

Regarding the removed comment, this solution idiom was discussed at
the time I made a similar fix to the rope implementation.  I'd rather
have this in ext code than explicit use of pthread_mutex_init.  For
one, some ports need (e.g.) -pthread even when linking single-threaded
code when the mutex is initialized by the function.  For two, it is an
abstraction violation.  Committed under general maintainer hat "as
obvious". (For the record: only tested under check-performance rule,
which I was porting to *-*-freebsd* at the time I found it, not full
bootstrap/check.)

	* include/ext/mt_allocator.h: Portability.

Index: libstdc++-v3/include/ext/mt_allocator.h
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/include/ext/mt_allocator.h,v
retrieving revision 1.1
diff -c -r1.1 mt_allocator.h
*** libstdc++-v3/include/ext/mt_allocator.h	11 Jun 2003 15:52:10 -0000	1.1
--- libstdc++-v3/include/ext/mt_allocator.h	24 Jun 2003 06:08:16 -0000
***************
*** 613,625 ****
            if (!_S_bin[bin].mutex) 
              __throw_bad_alloc();
  
!           /*
!            * This is not only ugly - it's extremly non-portable!
!            * However gthr.h does not currently provide a
!            * __gthread_mutex_init() call. The correct solution to
!            * this problem needs to be discussed.
!            */
!           pthread_mutex_init(_S_bin[bin].mutex, NULL);
  #endif
  
            for (size_t thread = 0; thread <= _S_max_threads; thread++)
--- 613,627 ----
            if (!_S_bin[bin].mutex) 
              __throw_bad_alloc();
  
! #ifdef __GTHREAD_MUTEX_INIT
! 	  {
! 	    // Do not copy a POSIX/gthr mutex once in use.
! 	    __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
! 	    *_S_bin[bin].mutex = __tmp;
! 	  }
! #else
! 	  { __GTHREAD_MUTEX_INIT_FUNCTION (_S_bin[bin].mutex); }
! #endif
  #endif
  
            for (size_t thread = 0; thread <= _S_max_threads; thread++)