qt5: bump version to 5.5.1

Reduce hash lists to strongest only (sha256).

Remove upstream committed patches (qt5base):
 - 0004-no-gold-linker-for-host-build.patch (see [1], [2])
 - 0007-big_endian-fix_destformat.patch (see [3])
 - 0008-QtGui-force-image-dir-in-include_path.patch (see [4], [5])

[1] https://bugreports.qt.io/browse/QTBUG-46125
[2] https://codereview.qt-project.org/#/c/113563/
[3] https://codereview.qt-project.org/#/c/120654/
[4] https://bugreports.qt.io/browse/QTBUG-47400
[5] https://codereview.qt-project.org/#/c/122145/



Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>