Fix broken rounded corner shader for cards

Program received signal SIGSEGV, Segmentation fault.
0x408f1d44 in QGLCustomShaderStage::setOnPainter(QPainter*) () from /usr/lib/libQtOpenGL.so.4
(gdb) bt
0  0x408f1d44 in QGLCustomShaderStage::setOnPainter(QPainter*) () from /usr/lib/libQtOpenGL.so.4
1  0x000c40e0 in CardLoading::paint (this=0x14672d8, painter=0xbed8ddfc, maximized=<optimized out>) at Src/lunaui/cards/CardLoading.cpp:264
2  0x000beddc in CardWindow::paint (this=0x14c8da0, painter=0xbed8ddfc, option=<optimized out>, widget=<optimized out>) at Src/lunaui/cards/CardWindow.cpp:1589
3  0x40c6b838 in ?? () from /usr/lib/libQtGui.so.4
4  0x40c6b838 in ?? () from /usr/lib/libQtGui.so.4
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Signed-off-by: Simon Busch <morphis@gravedo.de>