#250 typo in _fstream.c ( comparison instead of assignment )

[Myroslav Rubanets]

typo in _fstream.c:87
stlport/stl/_fstream.c:87:10: warning: self-comparison always evaluates to true
__ok == __ok && this->_M_unshift();
after looking around I think it was supposed to update '__ok' variable. so it shall look like this:
__ok = __ok && this->_M_unshift();

I found it in version 5.2.1 and verified that it is still in trunk.