[boost] [thread] SEVERE bug on packaged_task constructor in C++11 mode.

Hi, There is a severe bug in packaged_task constructor when compiling in C++11 mode and giving a copyable functor as parameter, as reported in https://svn.boost.org/trac/boost/ticket/8596. I believe that this is not a regression, this have never worked. Until I find a fix, the packaged_task could be used only with free functions and with movable functors when compiling in C++11 mode. Fortunately there is no regression on C++98 compilers (at least not identified yet). Sorry for the disagreement, Vicente