Compile error of Thread library with MipsPro 7.41

[Blake Richardson <barichards21@…>]

Running "make all" after running "/configure --with-libraries=thread" generates this compile error:

cc-3318 CC: ERROR File = ./boost/thread/pthread/thread.hpp, Line 208

A partial specialization of a member class template must be declared in the

class of which it is a member.

struct thread::thread_data<boost::reference_wrapper<F> >:

The MipsPro compiler does support partial specialization but I believe some extra initial declaration must be included.

[Anthony Williams]

I've extracted thread_data to a non-member type, so this should now work on trunk.