#130 Add CMake Check For The Need Of Libdl

[Mark McCurry]

-ldl is not needed on freebsd. Some check should be added to ensure that this lib is only linked on platforms which need it.

[falkTX]

there's a todo in there btw ;)
afaik it's needed by default, so we should add a check for specific platforms to disable it.

if (!win32 and !freebsd)
...etc

[Mark McCurry]

This should be fixed by 12b9ff886be32fb1976d992a5b0c9788c971fb39 thanks to HPS