[Mingw-cross-env-list] Qt 64-bit build working

[Tony Theodore]

Hello,

Qt is now building with (what turns out to be) some very small changes
- just two sed lines that can be tidied up later.

https://bitbucket.org/tonyt/mce-w64/changeset/b7df81bff3a7

I couldn't get postgresql to build yet, so it's disabled for the time
being. The test program runs okay (tested on Win7), and the demos that
build also run well. I didn't investigate the failing demos, the first
was unable to find one of it's own headers, and the next had linking
errors with a lib that it had just built - I gave up after that.
That's sixteen working, two failures, and five unknown.

I've switched to the release version of gcc and prepared tarballs of
binutils/mingw-w64, so there's no longer any need to checkout sources.

Cheers,

Tony