Third try at fixing build with older libvncclient versions.

This should fix c60c4cae5164de12a4c9910aa4cd85b199aec722, which should have
fixed e729c42ee9e77bbced1abfb712899dea2914b740...
Use pkg-config to detect Equalizer, to make it work with older Equalizer versions.
Set library directories from pkg-config.
Use the CMake information provided by Equalizer to find Equalizer; do not use pkg-config.

Both methods should work, but the solution without pkg-config is better
tested.
Merge branch 'master' of https://github.com/marlam/eqvnc