[Bug c++/52974] Canonicalize include paths in diagnostics

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52974

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-04-15 18:32:49 UTC ---
That was fast :)

I've only tested it lightly but it looks great, thank you very much.