Silenced GCC warnings about an initialized but not used variable.

svn path=/trunk/boost/uuid/; revision=78237
#included <string> for std::runtime_error constructor

svn path=/trunk/boost/uuid/; revision=80472
remove incorrect comment
try ignore_size() function to get rid of warning
initialize m_value in default constructor of generator_iterator

svn path=/trunk/boost/uuid/; revision=80501
fixed bug in sha1.hpp for messages longer than 536,870,912 bytes

svn path=/trunk/boost/uuid/; revision=80850