add support for x86_64-w64-mingw32 and cut the fat from libgcj

[Andrew Haley]

On 01/01/18 21:03, Yale Zhang wrote:
> Alright, I've submitted my request & patch to bugzilla:
>  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83647

I see it was rejected.  We could create a GCJ 6 branch.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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