net-wireless/bluez-4.99 will not build against udev-186. Sorry, I don't have a build log vecause I already have masked it on my system. Unfortunately the latest version of bluez (bluez-4.101) is broken and does not allow me to use my bluetooth. I am sure someone else will hit this and provide a build log.
Bug 423513 explains the problems with the 4.101 bluez version.
Bug 425002, Comment #1 *** This bug has been marked as a duplicate of bug 425002 ***