Patch for libstdc++ locale testing

[Paolo Carlini]

Hi,

>This patch fixes bugs 20448 (libstdc++ locale tests fail with
>--disable-nls) and 20451 (libstdc++ locale tests fail with multilib
>build-tree testing), by always having the test harness build the .mo
>files rather than relying on the Makefiles to do so.
>
thanks for tackling this long standing issue and sorry for late replying 
(connectivity problems...).

The patch is certainly fine with me, if you don't ear from the other 
library maintainers by the end of the day, just go ahead.

Thanks again,
Paolo.