Strange, I’ve just tried this on my Arch Linux system, with GCC 6.2.1 and Qt 4.8.7 (so same as you), and there’s no issue. But then in my case there is no mention of the /usr/include folder in the search path. I’d agree with the posts you mention, that it makes no sense to explicitly include the /usr/include folder, it’s a system folder and should already be in the default search path. But it’s a bit odd that things would therefore fall over when it’s included explicitly…
Regardless, I’m not too sure what’s causing this issue on your system, but very clearly the default Qt configuration on your system pulls in /usr/include (configure basically just reads what Qt’s qmake says will be included, as stated in the Makefile it generates) - this does’t happen on my system. But it’s difficult to get around given how tightly integrated the Qt auto-detection is to the configure script. One option to try is to install Qt5 and try with that version - I’d generally recommend using that version anyway, it’ll be better supported in the long run. The chances are, its version of qmake might produce a working Makefile, and sidestep the issue altogether - worth a try…