[Regression] Superscripted and special characters don't render properly

Several of the Qt examples fail to correctly render superscripted and other special characters, instead displaying them as a white question mark inside a black diamond. Affected examples include:

• examples/painting/painterpaths, where the "degrees" symbol in the last field is not displayed correctly
• examples/widgets/calculator, where the divide, multiply, x-squared and plus/minus buttons are not displayed correctly

This failure has been observed on both Windows 7 and Ubuntu Linux, so is presumed not to be platform-specific. The failure is not present in equivalent Qt 4.8.2 packages built with the same compilers, so is also presumed to be a regression.