"xinerama.h" file not found

Today I tried to build 5.8.0-beta on Ubuntu 14.04.5 LTS, configuring as follows: ./configure -commercial -no-icu -qt-xcb -prefix /usr/local/Trolltech/Qt-5.8.0-beta -nomake tests -no-openssl -opengl desktop -skip qtwebview -skip qtwebengine -skip qtwebsockets -skip qtwebchannel

Compilation stopped while building the xcb platform plugin complaining about a missing "xinerama.h" file. "sudo apt-get install libxcb-xinerama0-dev" fixed the issue.

As I configured with the -qt-xcb option I would think that the apt-get install call should not be neccessary.