Qbs: Fix qbs build syntax

Change-Id: Ifbfc128b3785941d0c6ec1789f1c85d2c602738a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
PNG: Fix warning about sRGB information

libpng 1.6 prints a line warning about this whenever loading any
of these files.

Remove color mangement related sections as well as time information
from the PNG files using:

pngcrush -rem gAMA -rem cHRM -rem iCCP -rem sRGB -rem time -force -ow FileName

PNGcrush is losslessly recompressing the files, too.

Change-Id: I483dfb98414c4914840bd5ee9318153a599747b1
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>