[Bug libstdc++/79156] incorrect c++ usage in gcc7 <memory> void function returns a value

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79156

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
In cases like this where it's just a dumb bug in our library headers (in a
non-standard extension which hadn't been adequately tested) we'd definitely
rather fix it here, not require other compilers to workaround it. Please do
continue to report any errors like this that you find, thanks.