Bitcoin-Qt: upgrade to Qt 4.8.4 for Windows builds #2108

For changes im Qt 4.8.4 see: http://blog.qt.digia.com/blog/2012/11/29/qt-4-8-4-released/

Automatic sanity-testing: PASSED, see http://jenkins.bluematt.me/pull-tester/e8c120cfeb81acd538bc10ae8834d136c55d2c8b for binaries and test log.

Any reason not to switch to latest Qt version?

Yes, it is time-consuming to rebuild dependencies for gitian, so when we do, I would rather we upgrade QT and boost and openssl any other dependencies (and maybe the OS we build on and the version of the compiler we use) all at once. The pain of changing dependencies is, I think, the reason we have so few people gitian-building releases, and that's a real problem.

I don't see any "must have" fixes in the QT 4.8.4 release notes.

@gavinandresen If you prefer batch dependency upgrades perhaps I should just include the latest Boost version also. I'm fine with creating that pulls, because at least in the Win-world it is (most of the time) essential to stay up-to-date (security and performance wise).

I took a look at Gitian also, but the howto setup was a real pain for me and I came to the conclusion that I currently don't want to spend too much time with it.

Automatic sanity-testing: PASSED, see http://jenkins.bluematt.me/pull-tester/e8c120cfeb81acd538bc10ae8834d136c55d2c8b for binaries and test log.

@gavinandresen So just to understand, when I create a patch to use Qt 4.8.4 does this require any manual or additional work for the core-devs who create the Gitian builds or does it just increase the compile-time once?

It requires manual/additional work. We have to rebuild our dependencies, and if the rebuilt dependencies have some non-determinism we have to spend time figuring out which of the dependencies is a problem and either fix it or just throw in the towel and trust one person's dependency to be correct.

Closed in favor of #2414