Removes install for example helper libraries

The libraries used to aid the example applications shouldn't be installed, should they?

-- Up-to-date: /usr/local/share/gloperate/examples/plugins/debug/libglobjects-paintersd.so
CMake Error at source/examples/globjects-painters/cmake_install.cmake:76 (file):
  file INSTALL cannot find
  "[...]/gloperate/source/examples/globjects-painters/include/globjects-painters".
Call Stack (most recent call first):
  source/examples/cmake_install.cmake:37 (include)
  source/cmake_install.cmake:42 (include)
  cmake_install.cmake:53 (include)


Makefile:69: recipe for target 'install' failed
make: *** [install] Error 1