Pyside2 5.9 Branch/QT 5.8/GCC 6.4/Linux - Build Failure

[GrandCentralDispatch]

Hi,

Im trying to build Pyside2, Shiboken2 (both 5.9 branch) on Linux with GCC 6.4 and Im getting

/usr/include/stdlib.h:33:10: fatal error: 'stddef.h' file not found

during shiboken's build.

This is the entire build log: https://gist.github.com/FictionIO/a275a0de30c86c09887527f86ab72f2a

[hhyyrylainen]

I had the same error with gcc 7.3. I ended up just using clang for compiling as that seemed to work:
CC=clang CXX=clang++ python setup.py build --qmake=/usr/bin/qmake-qt5 --ignore-git --build-tests --jobs=8