Occasional failures were observed in zconfig.sh because udev
could be delayed for a few seconds. To handle this the wait_udev
function has been added to wait for timeout seconds for an
expected device before returning an error. By default callers
currently use a 30 seconds timeout which should be much longer
than udev ever needs but not so long to worry the test suite
is hung.
Add autoconf style build infrastructure to the ZFS tree. This
includes autogen.sh, configure.ac, m4 macros, some scripts/*,
and makefiles for all the core ZFS components.