[patch libstdc++]: Add some missing errno-constants for mingw-targets

[Paolo Carlini]

Sorry,:
> Once more, I don't understand: didn't you suggest changing *only* 
> ENOSPC and EPERM? Why are we now discussing other error-numbers like 
> ECHILD, EAFNOSUPPORT and EBADMSG? Are the latter defined in errno.h?
should have written:

Once more, I don't understand: didn't you suggest changing *only* 
ECHILD, ENOSPC and EPERM? Why are we now discussing other error-numbers 
like EAFNOSUPPORT and EBADMSG? Are the former defined in errno.h?

Paolo.