undefined reference to `dlsym' - qt

Question

I'm trying to cross compile QT for the raspberry PI 3 under Debian Stretch but when I use make -j4 to compile QT, it gives the following error:
$ make -j4>log
/home/charlie/Rpi/qt5/qtbase/lib/libQt5EglSupport.a(qeglplatformcontext.o): In function `QEGLPlatformContext::getProcAddress(char const*)':
qeglplatformcontext.cpp:(.text+0xa4): undefined reference to `dlsym'
collect2: error: ld returned 1 exit status
make[5]: *** [../../../../plugins/platforms/libqminimalegl.so] Error 1
make[4]: *** [sub-minimalegl-make_first] Error 2
make[4]: *** Waiting for unfinished jobs....
/home/charlie/Rpi/qt5/qtbase/lib/libQt5EglSupport.a(qeglplatformcontext.o): In function `QEGLPlatformContext::getProcAddress(char const*)':
qeglplatformcontext.cpp:(.text+0xa4): undefined reference to `dlsym'
collect2: error: ld returned 1 exit status
make[6]: *** [../../../../lib/libQt5EglFSDeviceIntegration.so.5.8.1] Error 1
make[5]: *** [sub-eglfsdeviceintegration-pro-make_first-ordered] Error 2
make[4]: *** [sub-eglfs-make_first] Error 2
make[3]: *** [sub-platforms-make_first] Error 2
make[2]: *** [sub-plugins-make_first] Error 2
make[1]: *** [sub-src-make_first] Error 2
make: *** [module-qtbase-make_first] Error 2
I have read a lot of similar posts containing the same dlsym error and I have tried the solutions given in them, but no luck so far. I have proceeded as it is shown in here and until now I still have doubts about the symlinks in lib directory.
When I run sudo file * | grep broken, 2 symlinks are reported to be broken, even after running the script that supposedly fixes the symlinks (as sudo).
./fixQualifiedLibraryPaths /mnt/raspberry-rootfs/ ~/Rpi/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf-gcc
The symlinks that appear to be broken are listed below:
libblas.so.3gf: broken symbolic link to /etc/alternatives/libblas.so.3gf
liblapack.so.3gf: broken symbolic link to /etc/alternatives/liblapack.so.3gf
The ./configure is executed as follows:
./configure -opengl es2 -device linux-rasp-pi-g++ -device-option CROSS_COMPILE=~/Rpi/gcc-4.7-linaro-rpi-gnueabihf/bin/arm-linux-gnueabihf- -sysroot /mnt/raspberry-rootfs -opensource -confirm-license -optimized-qmake -reduce-exports -release -make libs -prefix /usr/local/qt5pi -hostprefix /usr/local/qt5pi
Do you guys can point me out what I am doing wroing?
PD: I also installed the libncurses5 and lib32z1 and I obtained qt by git cloning.

Answer 1

I ran into the same problem, proceeding as you did but using the gcc-5.4.1-linaro-gnueabihf toolchain. Unfortunately I did not find the root cause, but a workaround is calling configure like
LIBS=-ldl ./configure ...

Answer 2

with raspbian stretch egl libs has different names
/opt/vc/lib/libEGL.so -> /opt/vc/lib/libbrcmEGL.so
/opt/vc/lib/libGLESv2.so -> /opt/vc/lib/libbrcmGLESv2.so
so, I eddited this file in Qt sources:
./qtbase/mkspecs/devices/linux-rasp-pi3-g++/qmake.conf
and changed
-lEGL -lGLESv2
to
-lbrcmEGL -lbrcmGLESv2

Answer 3

the symlinks was broken when mount to host,
$ cd /mnt/raspberry-rootfs/usr/lib/arm-linux-gnueabihf/
$ sudo rm libdl.so
$ sudo ln -s ../../../lib/arm-linux-gnueabihf/libdl.so.2 libdl.so

Answer 4

I faced the same issue, tried to follow Miguel Angel Pons solution, but then realized that missed to update my raspberry with:
sudo rpi-update
Solution is taken from https://wiki.qt.io/RaspberryPi2EGLFS#Step_by_step. It is refferencing to https://bugreports.qt.io/browse/QTBUG-62216 and should fix the libraries exactly which compiler complains to.
After that I repeated 8 and 9 steps, cleaned up the source tree, reconfigured and finally successfully built qt for raspberry.