[Bug libstdc++/61761] [C++11] std::proj returns incorrect values

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61761

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I probably missed a later fix that got made to the trunk version of the test.
I'll take a look.