The new avahi-0.6.1 breaks API/ABI-compatibility with the 0.5-series and although vlc does not depend on it in the ebuild, it will be enabled by default if the avahi-library gets found by the configure-script and will fail to compile with the new version. So there are two resolutions, correct the ebuild and make it depend with use flag on avahi-0.5* or disable it explicitely with --disable-bonjour. If the devs want, I could post the compilation error. steps to reproduce install avahi-0.6.1, rebuild vlc.
Thanks for reporting, currently disabled to avoid issues, until a new solution is found.