The package dev-libs/DirectFB-1.4.9-r1 should have a USE flag called sysfs, which controls whether the package depends on sys-fs/sysfsutils. Right now, this is implicit. The build (without sysfsutils) will do this: checking for sysfs_get_mnt_path in -lsysfs... no configure: WARNING: *** libsysfs not found -- Building without sysfs support. If DirectFB is built with when sysfsutils is installed, DirectFB will depend on sysfsutils and break when it is uninstalled. It will be found by revdep-rebuild, but I would prefer the dependency on sysfs to be explicit so that it will be handled by emerge.
according to bug #377681 sys-fs/sysfsutils is going to be removed from the tree