X11 native painting fails to build when fontconfig=no.

QtBase dev branch at 593719aab581ef82489565e71ace8bda77dcf933.
Relatively fresh install of Ubuntu 16.04, with the following packages (IIRC) installed on top:

sudo apt-get install libxcb-xinerama0-dev
sudo apt-get install build-essential perl python git
sudo apt-get install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev

Qt configured with:

./configure -developer-build -debug -nomake examples -nomake tests

See the attached configure.summary and build failure log files.

If I install:

sudo apt-get install libfontconfig1-dev

fontconfig=no becomes fontconfig=yes and build succeeds.