* HOW TO BUILD
  
  step 1. apply build path using 
  >> source env.sh
  
  step 2. build libvncserver
  >> cd ext_dep/libvncserver
  >> mkdir build
  >> cd build
  >> cmake ..
  >> cmake --build .
  
  step 3. copy libvncserver library to root
  >> cd ext_dep/libvncserver/build
  >> cp -a libvncserver* ../../..
  
  step 4. bulid project with make
  >> make clean; make