tabWidget_fractals->setUsesScrollButtons(true); tabWidget_fractals->setDocumentMode(true); tabWidget_fractals->setElideMode(Qt::ElideNone);
This error comes from lack of system (RAM) memory. To compile render_window.cpp there is needed about 1GB of RAM.
g++: internal compiler error: Getötet (program cc1plus) Please submit a full bug report, with preprocessed source if appropriate. See file:///usr/share/doc/gcc-4.9/README.Bugs for instructions. Makefile:3268: recipe for target 'render_window.o' failed
As you see it's internal compiler error, which is probably caused by not enough memory.
@zebastian had the same problem with rpi.
There are two possible solutions: