[Bug libstdc++/51617] [C++0x] async(f) isn't.

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51617

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-12-19 11:13:25 UTC ---
That would require a global integer somewhere to count the threads, which would
probably have to be kept forever to maintain ABI compatibility.  If I had time
to implement a temporary semi-intelligent fix then I'd rather just do it
properly instead :)