Large number of PNG images with incorrect color profiles and other bugs

The Qt sourcecode contains large numbers of broken PNG images. These cause warnings from libpng to be printed to stderr when running any Qt application. Simply creating a QWebView and settings its URL to about:blank causes such a warning, for example:

python -c "from PyQt5.Qt import *; app = QApplication([]); s = QWebView(); s.setUrl(QUrl('about:blank'))"
libpng warning: iCCP: Not recognizing known sRGB profile that has been edited

A list of such broken PNG images in the source tree can be generated like this:

find . -name '*.png' -exec identify {} \; | grep MagickPNGWarningHandler

Most of these warnings can be fixed by simply removing the broken embedded color profile like this:

convert file.png -strip fixedfile.png