Qt5.5 - Missing Compilers

I just downloaded and installed Qt 5.5 and in the Qt Versions tab it has a complaint about Qt 5.5.0 for iOS, it says, "Not all possible target environments may be supported due to lack of compilers." If I hover over this message it says "The following ABIs are not currently supported: arm-macos-generic-mach_o-64bit"

I'm not even sure what the message is telling me, is it saying the ABI doesn't exist at all? Or is it just that Qt5 can't handle it yet?

And how can I determine which is the right compiler to install?

This is also unfortunate on the Android side, it prevents me from building for Android / x86. On the Android tab in the Preferences it says "there are no Qt versions for 4 architectures. To add Qt versions go to Options> Build & Run> Qt Variants. I'll go there and it shows a whole flock of Android GCC compilers, including one for x86_64-4.9, but in the "Qt Versions" tab, the only Qt for Android is for armv7. If I click Add, it asks me which qmake to use and there is no qmake for android_x86. How create qmake for android / x86?