c++/3385: -std=foo doesn't work with C++

[Neil Booth]

Joseph S. Myers wrote:-

> It would make sense to support -std for C++, with possible values being 
> iso14882:1998 and g++98, but it's never going to make sense to specify a C 
> standard (ISO 9899) version when compiling C++, and there ought to be 
> appropriate errors given if you try to do so; the lack of error messages 
> is a bug.

cpplib supports "-std=c++98", so we should stick with that.  I don't
see the value in the really verbose forms.

Neil.