Make all udev tools dynamically link to libudev.so

Move libudev.so back to $(rootlibdir) for lvm2 support, and have
all udev tools dynamically link to it.  The symbol versioning and
hidden-visibility on libudev were modified accordingly: we rebase
against the public LIBUDEV_196 symbol versioning, and marked all
other symbols (which used to be local) as  LIBUDEV_internal.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>