Update QT to 4.8.6

The current version can't be downloaded any more:

Downloading http://download.qt-project.org/official_releases/qt/4.8/4.8.5/qt-everywhere-opensource-src-4.8.5.tar.gz...
[ERROR] urllib failed to download (code: 404): http://download.qt-project.org/official_releases/qt/4.8/4.8.5/qt-everywhere-opensource-src-4.8.5.tar.gz

And the new version 5.3.1 doesn't compile with the current build script.
Qt: Use more permanent URL

Per @ahmadia's suggestion. I checked the hash, it did not change.
Make Qt non-relocatable
Merge pull request #381 from hashdist/qt

Update QT to 4.8.6