[Bug c++/59675] -D_GLIBCXX_DEBUG asserts to stdout (it should stderr)

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59675

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Seems obviously correct, I don't know/remember if there was a reason stdout was
used