Thanks for the nice suggestions. I changed the cmake configuration not to use external toolchain compilers. Instead I installed arm-gnueabihf-gcc-4.8 and arm-gnueabihf-g+±4.8 using this command:
sudo apt-get install gcc-arm-linux-gnueabihf
and
sudo apt-get install g+±arm-linux-gnueabihf
It compiled successfully. However when I run objdump command with cross compiled libs it stills prints architecture as “unknown”. I was expecting “arm”. However QT did not complain this time and built the project. When I copied the built binary it also run successfully on RaspberryPi 2.