[Bug c++/85958] Make const qualifier error clear

[jg at jguk dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85958

--- Comment #1 from Jonny Grant <jg at jguk dot org> ---
My idea of what would be clearest is :-

Cannot pass ‘const int‘ as ‘int&‘ (non const)