1.) The check for "QT_USES_X11" expects the created application
to run, but the '.exe' file does not run on linux.
2.) Don't use megered build anymore, it is not faster
on multi-processor machines anyway
As discussed on the list. If no C++11 compiler is found configuration stops
with an error. There are now unneeded parts of boost, the will be removed in
a second commit.
Nothing changes for already cached values.
With fresh build-dir and in 'AUTO'-mode we try to determine if the c++ compiler
is able to use this feature.
