[RFA/commit] Set default target-wide-charset setting to "UTF-16" for x86_64-windows.

[Joel Brobecker]

> Shouldn't this be "UTF-16LE"?  Or is "LE" the default?

Not in this case, because GDB takes care of adding the "LE" suffix
for us, based on the target endianness. I guess that might be useful
on platforms that can execute code following either endianness.

-- 
Joel