Force gray-antialiasing for text.

Subpixel antialiasing cannot be supported when rendering is done
to a transparent-cleared FBO.

Change-Id: I46eeac792416f6164521c9142a8b6cffbbddc99b
Reviewed-by: Marco Bubke <marco.bubke@digia.com>

share/qtcreator/qml/qmlpuppet/qml2puppet/qml2puppetmain.cpp

@@ -47,6 +47,10 @@
 
 int main(int argc, char *argv[])
 {
+    // Since we always render text into an FBO, we need to globally disable
+    // subpixel antialiasing and instead use gray.
+    qputenv("QSG_DISTANCEFIELD_ANTIALIASING", "gray");
+
     QApplication application(argc, argv);
 
     QCoreApplication::setOrganizationName("QtProject");