[v3] libstdc++/18571

[Paolo Carlini]

Benjamin Kosnik wrote:

>this is the second of four parts. 
>
>This a consolidation of the codecvt specialization code, moving it to an
>optional extension. Because of this, it is no longer a somewhat
>ill-fitting part of the current locale configuration. 
>  
>
Thanks. Therefore, I understand that later parts will deal with the 
remnants of
_GLIBCXX_USE___ENC_TRAITS in the testsuite? (just noticed, by chance)

Paolo.