Add Patch to make qtstandardpaths configurable

* Makefile.am (EXTRA_DIST): Add patch.
* patches/qtbase-5.5.1/config-standardpaths.patch: New.

QStandardPaths is in a bad state by default. It writes config
data into %LOCALAPPDATA% (without subdir) which does not make
sense at all.

This patch makes it possible to change this with a qt.conf file