libQtGui fails linking libqtpng on Power8+ and Power9

I cannot link libQtGui as it complains that libqtpng has an undefined reference to png_init_filter_functions_vsx.

Commenting out qtbase/src/3rdparty/libpng/pngpriv.h:266 (just this one line) works around the issue.

Here is the short-form of the output. I attached the full logs:
configure -prefix /sw/summitdev/qt/5.10.1/rhel7.3_gnu4.8.5 -no-opengl -no-compile-examples
...
make -j4
...
g++ ... -o libQt5Gui.so... -lQt5Core -lpthread -lqtlibpng -lqtharfbuzz -lz
~/brendel/qt-everywhere-src-5.10.1-unmodified/BUILD/qtbase/lib/libqtlibpng.a(pngrutil.o): In function `png_read_filter_row':
pngrutil.c: (.text+0x5e44): undefined reference to `png_init_filter_functions_vsx'
/usr/bin/ld: link errors found, deleting executable `libQt5Gui.so.5.10.1'

Thank you in advance!