bug#43579: g++ does not provide std::fegetround

[Ricardo Wurmus]

Hi,

I just rediscovered this issue by adding “gcc-7” to a package’s input
without also adjusting the variable that determines the order of
includes.  (I ended up not needing to use GCC 7 in the end.)

Seeing that issue #42392 (“GCC includes ordering issue? g++: error:
'round' is not a member of 'std'”) has since been solved, should we
close this issue, too?

Or are there still reasons to want an adjustment of the
gnu-build-system?  What do you think, Miguel?

-- 
Ricardo