Configuring qt5.8 build with directfb without pkg-config is not working

configuring qt build with directfb support is not working

configure command

./configure -v -opensource -confirm-license -release -strip -shared -prefix /home/ankit/rooster_poc//qt/Rooster4/ -extprefix /home/ankit/rooster_poc//qt/Rooster4/ -device linux-Rooster4-g++ -device-option CROSS_COMPILE=/home/ankit/rooster_poc//ndk/platforms/Rooster4/toolchain/bin/arm-brcm-linux-gnueabi- -sysroot /home/ankit/rooster_poc//ndk/platforms/Rooster4/toolchain/arm-brcm-linux-gnueabi/sysroot/ -qpa directfb -directfb -reduce-exports -qt-sqlite -no-opengl -skip qtwebengine -no-dbus -ssl -no-cups -no-fontconfig -no-gtk -no-harfbuzz -no-compile-examples -no-pch -no-glib

DirectFB failure

Checking for DirectFB... 
Trying source 0 (type pkgConfig) of library directfb ...
pkg-config use disabled globally.
  => source produced no result.
test config.gui.libraries.directfb FAILED

Even if qconfig.pri has following lines indicating pkg-config enabled

QT.global.enabled_features = shared rpath accessibility c++11 c++14 concurrent pkg-config
QT.global.disabled_features = framework debug_and_release simulator_and_device build_all c++1z force_asserts separate_debug_info static 

Problem:

• There is only source 0 (pkg-config) , why there is no other check for directfb?
• It works fine with older version of Qt(4.7.4) using qmake.conf with QT_CFLAGS_DIRECTFB and QT_LIBS_DIRECTFB variables, same is ignored in Qt 5.8.0 build (as mentioned in http://doc.qt.io/qt-4.8/qt-embeddedlinux-directfb.html)

Expected:

• pkg-config should be honored when available
• There has to be an alternate way to use directfb support other than pkg-config
• When cross compiled without sysroot using -xplatform flag there is no way to use directfb because in absence of sysroot pkg-config is disabled