RPM and shared lib improvements

These changes:
1. allow dashel packages for the latest Fedora and OpenSUSE to be built on the OpenSUSE build server. 2. make the dashel shared lib dynamically link to EXTRA_LIBS (e.g. libudev.so) which should mean that programs which link with dashel won't also need to link with EXTRA_LIBS (unless they access those libs directly). I've tested this on Fedora, and am pretty confident that it will work on other Linux distros, but don't know about (and can't test) on Win32 and Apple.