[Bug libstdc++/84535] std::thread constructor missing constraint on first argument

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84535

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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   Target Milestone|9.0                         |8.3

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for GCC 8.3 too.