[Bug libstdc++/86513] ostringstream default constructor missing from libstdc++

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86513

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
OK, I was just going by what you said:

(In reply to Csaba Ráduly from comment #3)
> [...] my usual "svn up && make bootstrap && make install" [...]