Okay, I tried building Qt 5.7 without ANGLE, which is the part of Qt that's supposed to use Direct3D. Tested on a Windows XP virtual machine and it's still complaining about the missing entry point. Tried building against Qt 5.1, and it seems to work:
I'm tempted to use Qt 5.1 for the official build too, but I know newer versions of Qt often include a bunch of important compatibility updates for newer operating systems, so I'm a little wary of doing that. In the meantime, the build above should work for you.